Reprise: Is Muzzle Energy Really a Measure of Handgun Effectiveness?

Prompted by my friends over at the Liberal Gun Club, this is another in an occasional series of revisiting some of my old articles which had been published elsewhere over the years, perhaps lightly edited or updated with my current thoughts on the topic discussed. This is an article I wrote for Guns.com, and it originally ran 2/13/2012. Some additional observations at the end.

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Would you rather be shot with a modern, Jacketed Hollow Point bullet from a .32 ACP or have someone throw a baseball at you? Seems like a silly question, doesn’t it? But did you know that the ‘muzzle energy’ of the two is about the same? Seriously, it is and that’s just one reason why trying to use muzzle energy as a measurement of handgun effectiveness is problematic.

Calculating Muzzle Energy

First off, what is ‘muzzle energy’ (ME)? Wikipedia has a pretty good description and discussion of it. Here’s the simple definition:

Muzzle energy is the kinetic energy of a bullet as it is expelled from the muzzle of a firearm. It is often used as a rough indication of the destructive potential of a given firearm or load. The heavier the bullet and the faster it moves, the higher its muzzle energy and the more damage it will do.

For those who are trying to remember your high school physics, kinetic energy is the energy (or power) of something moving. You can calculate kinetic energy using the classic formula:

E = 1/2mv^2

Which is just mathematic notation for “Energy equals one-half the mass of an object times the square of its velocity.”

Doing the actual calculations can be a bit of a pain, since you have to convert everything into consistent units, but the formula is there on the Wikipedia page (and can be found elsewhere) if you want to give it a go. Fortunately, there are a number of websites out there which will calculate muzzle energy for you – you just plug in the relevant numbers and out comes the result. We also have muzzle energy graphs for all the calibers/ammunition tested at BBTI.

Batter up?

If you go through and check all the muzzle energy numbers for handguns with a 6″ or less barrel which we’ve tested (BBTI that is), in .22, .25. or .32, you’ll see that all except one (and you’ll have to go to the site to see which one it is) comes in under 111 foot-pounds.

Why did I choose that number? Because that would be the kinetic energy of a baseball thrown at 100 mph. Check my numbers: a standard baseball weighs 5.25 ounces, which is about 2,315 grains. 100 mph is about 147 fps. That means the kinetic energy of a baseball thrown at 100 mph is 111 ft-lbs.

Now, we’re not all pro baseball pitchers. And I really wouldn’t want to just stand there and let someone throw a baseball at me. But I would much rather risk a broken bone or a concussion over the damage that even a small caliber handgun would do.

The Trouble with Muzzle Energy

And therein lies the problem with using muzzle energy as the defining standard to measure effectiveness: it doesn’t really tell you anything about penetration. A baseball is large enough that even in the hands of Justin Verlander it’s not going to penetrate my chest and poke a hole in my heart or some other vital organ. If I catch one to the head, it may well break facial bones or even crack my skull, but I’d have a pretty good chance of surviving it.

Now, I think muzzle energy is a useful measure of how much power a given handgun has. That’s why we have it available for all the testing we’ve done on BBTI. But it is just one tool, and has to be taken into consideration with other relevant measures in order to decide the effectiveness of a given gun or caliber/cartridge. Like measures such as depth of penetration. And temporary and permanent wound channels. And accuracy in the hands of the shooter. And ease of follow-up shots. And ease of carry.

I’ve seen any number of schemes people have come up with to try and quantify all the different factors so that you can objectively determine the “best” handgun for self defense. Some are interesting, but I think they all miss the point that it is an inherently subjective matter, where each individual has to weigh their own different needs and abilities.

Sure, muzzle energy is a factor to consider. But I think the old adage of “location (where a bullet hits) is king, and penetration is queen” sums it up nicely.

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In the five years since I wrote that, my thinking has evolved somewhat. Well, perhaps it is better to say that it has ‘expanded’. I still agree with everything above, but I’m now even more inclined to go with a relatively heavy bullet for penetration over impressive ME numbers. I think that comes from shooting a number of different brands of ammo where the manufacturer has chosen to go with a very fast, but very light bullet to get an amazing ME, with the argument that this is more likely to cause some kind of terminal shock, citing tests showing significant ‘temporary wound channels’ and such in ballistic gel.

But you really can’t cheat physics. If you dump a lot of kinetic energy very quickly into creating a temporary wound channel, then you have less energy for other things. Like penetration. Or bullet expansion. And those are factors which are considered important in how well a handgun bullet performs in stopping an attacker. That’s why the seminal FBI research paper on the topic says this:

Kinetic energy does not wound. Temporary cavity does not wound. The much discussed “shock” of bullet impact is a fable and “knock down” power is a myth. The critical element is penetration. The bullet must pass through the large, blood bearing organs and be of sufficient diameter to promote rapid bleeding. Penetration less than 12 inches is too little, and, in the words of two of the participants in the1987 Wound Ballistics Workshop, “too little penetration will get you killed.” Given desirable and reliable penetration, the only way to increase bullet effectiveness is to increase the severity of the wound by increasing the size of hole made by the bullet. Any bullet which will not penetrate through vital organs from less than optimal angles is not acceptable. Of those that will penetrate, the edge is always with the bigger bullet.

 

Now, you can still argue over the relative merits of the size of the bullet, and whether a 9mm or a .45 is more effective. You can argue about trade-offs between recoil & round count. About this or that bullet design. Those are all completely valid factors to consider from everything I have seen and learned about ballistics, and there’s plenty of room for debate.

But me, I want to make sure that at the very minimum, the defensive ammo I carry will 1) penetrate and 2) expand reliably when shot out of my gun. And if you can’t demonstrate that in ballistic gel tests, I don’t care how impressive the velocity of the ammo is or how big the temporary wound cavity is.

So I’ll stick with my ‘standard for caliber’ weight bullets, thanks. Now, if I can drive those faster and still maintain control of my defensive gun, then I will do so. Because, yeah, some Muzzle Energy curves are better than others.

 

Jim Downey

Reprise: It’s Not the Length of Your Barrel, It’s How You Use It

My friends over at the Liberal Gun Club asked if they could have my BBTI blog entries cross-posted on their site. This is another in an occasional series of revisiting some of my old articles which had been published elsewhere over the years, perhaps lightly edited or updated with my current thoughts on the topic discussed. This is an article I wrote for Guns.com, and it originally ran 3/7/2011. Some additional observations at the end.

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“What is the best barrel length?”

It’s a question I get a lot, thanks to my involvement in Ballistics By The Inch. And invariably, I say in response: “it depends.” As in, it depends on what you’re going to use it for.

OK, first thing: I’m talking about pistol cartridges, not rifle cartridges. Got that? Pistol cartridges.

That’s what we studied with our BBTI project (actually, continue to study, since we’ve done several expansions of the cartridges and ammunition tested already, and have another big expansion coming up the beginning of May.) Now that we’ve cleared that up . . .

Different barrel lengths are good for different purposes. The longer the barrel, the longer the sight radius, and so the easier it is to be accurate with the gun. The shorter the barrel, the easier it is to conceal.

And barrel length has an effect on the velocity of a bullet (and hence the power of that bullet.) How much of an effect? Well, it depends.

No, seriously, it depends. Do not believe it when someone tells you “oh, the rule of thumb is about 75 (or 25 or 100 or any other number) feet per second for each inch of barrel.” That number may be right for one given ammunition in one given gun for one given inch of barrel length – but it will not hold true as a general case. Don’t just take my word on this – look at the actual numbers from tests we conducted, using almost 10,000 rounds of ammunition. You can go to the BBTI site and see the data for yourself (it’s all free, with no advertising or anything), but here are two examples:

Cor Bon 165gr JHP +P .45 ACP ammo was tested at 1001 fps with a 2″ barrel. That jumps to 1050 fps with a 3″ barrel, or an increase of about 50 fps. Going to a 4″ barrel you get 1163 fps, or an increase of 113 fps. But when you go from an 10″ barrel to a 11″ barrel, you only get an increase of 23 fps.

Let’s look at Federal Hydra-Shok 230gr JHP .45 ACP. It starts at 754 fps with a 2″ barrel, and jumps to 787 fps out of a 3″ barrel – an increase of 33 fps.  Go to the 4″ barrel and it tested at 865 fps – an increase of 78 fps. And when you go from an 10″ barrel to a 11″ barrel, you only get an increase of 4 fps.

Do you see my point? It not only varies by ammunition, it also varies by which inch of the barrel you are talking about – the inch between 3 and 4 sees a lot more increase than the inch between 10 and 11.

Almost all handgun cartridges show this effect, and it makes sense: pistol cartridges use a fast burning powder, but it still needs a little bit of time to completely combust. The highest acceleration comes at first, and then usually handgun bullets plateau out somewhere between 6″ and 10″, with little additional velocity with longer barrels past that point. The graph of our first example shows this very well:

Some cartridges even show velocity starting to drop off with longer barrels, as the friction of the bullet passing through the barrel overcomes any additional boost from the gunpowder. Notably, the “magnum” cartridges (.327, .357, .41, and .44) all show a continued climb in velocity/power all the way out to 18″ of barrel length (the maximum we test), though the amount of increase tends to get smaller and smaller the longer the barrel.

So, back to “it depends”: if you want a lever-gun or carbine, which uses a pistol cartridge, you’re best off using one of the magnums if you want maximum power. If, however, you want to use a carbine for an additional power boost and better aiming, one with a barrel length somewhere in the “plateau” for a given cartridge makes sense (and this is why subguns typically have barrels in the 8 – 10″ range).

For a hunting pistol, you probably want to have a barrel of 6″ to 8″ to get a lot of the additional power and still have it manageable. This barrel length will also give you a nice big sight radius for accuracy, making it good for hunting or target shooting.

How about for concealed carry? The shorter the barrel, the better, right? Well, if you look through all our data, you’ll see that usually, most cartridges see the greatest jump in velocity (and hence power) from 2″ to 4″. Now, the smaller the caliber and the lighter the bullet, the more the big jump tends to come right up front – from 2″ to 3″. The larger the caliber and the heavier the bullet, the more it tends to come a little later, from 3″ to 4″. Still, you can decide for yourself whether the trade-off in less power for ease of carry is worth it.

And good news for the revolver fans: because the cylinder basically functions to extend the barrel, your 2″ snubby actually functions more like a gun with a 3.5″ – 4″ barrel. Though there is some velocity/power loss due to the cylinder gap. How much loss? That is actually the next thing we’ll be testing, but I’d bet that . . . it depends.

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Since I wrote that six years ago, we’ve done a LOT more testing at BBTI, and have now shot more than 25,000 rounds and greatly expanded our data. The cylinder gap tests mentioned above did indeed show that the amount of loss did vary according to a number of factors, but for the most part established that the effect wasn’t as large as many people thought. And we found an interesting exception to the “magnum” rule in one of our most recent tests: it turns out that the .45 Super cartridge behaves like a true magnum, by continuing to gain more power the longer the barrel, until at carbine lengths it is on a par with (or even exceeds) the .460 Rowland cartridge. Since the .45 Super is based on the .45 ACP cartridge, we expected it to perform like that cartridge and level off at about 10″, but it clearly continues to gain out to at least 18″.

I also want to add a couple of quick comments about how concealed-carry guns have changed, though this is more just personal observation than any kind of rigorous research. I think that as concealed-carry has continued to expand, more gear is on the market to make it easier to do, and I think for that reason some people are able to carry slightly larger guns and there are more guns available with barrel length in the 4″ – 5″ range. In addition, sight/optics/laser options have continued to improve, making simple sight radius less of a factor — meaning that for those who do want to carry a smaller gun, it is easier to use it well (though having better sights/optics/lasers is NOT a substitute for practice!) I expect that both these trends will continue.

Jim Downey

Reprise: So, You Say You Want Some Self-Defense Ammo?

My friends over at the Liberal Gun Club asked if they could have my BBTI blog entries cross-posted on their site. This is the second in an occasional series of revisiting some of my old articles which had been published elsewhere over the years, perhaps lightly edited or updated with my current thoughts on the topic discussed. This is an article I wrote for Guns.com, and it originally ran 2/16/2011. Some additional observations at the end.

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You need to choose self-defense ammunition for your gun. Simple, right? Just get the biggest, the baddest, the most powerful ammunition in the correct caliber for your gun, and you’re set, right?

Wrong. Wrong, on so many levels.  For a whole bunch of reasons. We’ll get to that.

Shooters have earned the reputation as an opinionated breed and arguments over ammunition are a staple of firearms discussions, and have been for at least the last couple of decades. Much of this stems from the fact that every week it seems, you’ll see “fresh” claims from manufacturers touting this new bullet design or that new improvement to the gunpowder purportedly to maximize power or minimize flash.  And the truth is there have been a lot of improvements to ammunition in recent years, but, if you don’t cut through the hype you can easily find yourself over-emphasizing the importance of featured improvement in any given ammunition.

Perhaps it’s best to consider it by way of example.  While the basic hollowpoint design has been around since the 19th century, I remember when simple wadcutters or ball ammunition was about all that was available for most handguns. Cagey folks would sometimes score the front of a wadcutter with a knife (sometimes in a precarious manner—please don’t do this Taxi Driver-style with live ammunition) to help it ‘open up’ on impact. Jacketed soft point ammunition was considered “high tech” and thus distrusted. And yet, these simple bullets stopped a lot of attacks, killed a lot of people and saved a lot of lives.

I’m not saying that you don’t want good, modern, self-defense ammunition. You probably do. I sure as hell do. I want a bullet designed to open up to maximum size and still penetrate properly at the velocity expected when using it. If you are ever in a situation where you need to use a firearm for self-defense, you want it to be as effective as possible in stopping a threat, as quickly as possible.

Modern firearms are not magic wands. They are not science-fiction zap guns. How they work is they cause a small piece of metal to impact a body with a variable amount of force. That small piece of metal can cause more or less damage, depending on what it hits and how hard, and how the bullet behaves. Here’s the key that a lot of people forget: as a general rule, location trumps power.  All you have to do is meditate on the fact that a miss with a .44 magnum is nowhere  near as effective as a hit with a .25 ACP.  And when I say “a miss” I’m talking about any shot which does not hit the central nervous system, a major organ, or a main blood vessel (and even then it matters exactly which of these are hit, and how). Plenty of people have recovered from being shot multiple times with a .45. Plenty of people have been killed by a well-placed .22 round.

Hitting your target is what is most important and for most of us that is harder to do with over-powered ammunition we’re not used to shooting regularly. Chances are that under the stress of an actual encounter, your first shot may not be effective at stopping an attack. That means follow-up shots will be needed, and you’d better be able to do so accurately. If you can’t get back on target because of extreme recoil, then what’s the point of all that extra power?  If you can’t get back on target because you’ve been blinded by the flash of extra powder burning after it leaves the muzzle, well hell, that’s not good either.

Nestled up alongside power is having an ammunition that will actually work well in your gun. Some guns are notoriously ammunition sensitive and you  don’t want to just be finding out  your gun doesn’t particularly care for an ammo when you really need it to go boom. Check with others (friends or online forums) who have your type of gun, and see what ammo works for them. Then test it yourself, in your actual gun. Some people won’t carry a particular ammunition until they have run a couple of hundred rounds of that ammunition through their gun. Personally, I’ll run a box or two through the gun and consider that sufficient;  you’ll know after that if your gun generally handles  that ammunition with any problems.

So, once you have an idea of what ammunition will work in your particular gun, how do you choose between brands? As I’ve previously discussed, you can’t necessarily trust manufacturer hype. So, how to judge?

Well, you can do some research online. The fellows at The Box of Truth have done a lot of informal testing of ammunition to see how different rounds penetrate and perform. The Brass Fetcher has done a lot of more formal testing using ballistic gelatin. Ballistics By The Inch (which is yours truly’s site) has a lot of data showing velocity for different ammunition. And most gun forums will have anecdotal testing done by members, which can provide a lot of insight.

But don’t over-think this. Handguns are handguns. Yeah, some are more powerful than others, but all are compromises – hitting your target is the single most important thing. And like I said, ammunition can help, but only to a certain extent. We’re talking marginal benefits, at best, whatever the manufacturers claim. So relax;  all of the big name brands are probably adequate, and you’d be hard pressed to make a truly bad decision, so long as the ammunition will function reliably in your gun and you can hit your target with it.

Of course, as you do more research, and get more experience, you’ll probably find you like some ammunition more than others, for whatever reason. That’s fine. It just means that you’re ready to join in the (generally genial) arguments over such matters with other firearms owners. Welcome to the club.

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Some additional thoughts, six years later …

Bullet design has continued to improve, with new and occasionally odd-looking designs and materials being introduced regularly. Some of these are *really* interesting, but I keep coming back to the basic truth that the most important factor is hitting the target. No super-corkscrew-unobtanium bullet designed to penetrate all known barriers but still stop inside a bad guy is worth a damn if you miss hitting your target.

And that means practice (and training, if appropriate) is more important than hardware. What I, and a lot of shooters concerned about their self-defense skill, will do is to use practice ammo for training when they go to the range, to keep their basic skill set honed. And then supplement that with a magazine or two (or a cylinder or two) of their carry ammo, so they refresh their knowledge of how it feels and behaves in their gun. This can help keep practice costs down (since good SD ammo can be expensive), but also keeps carry ammo fresh.

Jim Downey

Much more black powder fun!

A couple of summers ago, I got together with some friends and we did a little black powder shooting. Well, since then we’ve talked about getting together again with even more great historical guns (reproductions) and another shooting buddy, and this past weekend we did just that.

Did I say more guns? Why, yes, I did:

Total of 21 shown, with one extra hiding in that brown case in the second pic.

I’m not going to try and give a real review of every one, but using the two pics above I will identify each gun, maybe add another pic or two of it in action, and provide some initial impressions of shooting it. So, without further ado, starting with the top image:

Top gun: Early Matchlock Caliver. .62 ball, 60gr FFg. A pleasure to shoot. This felt less bulky than the earlier guns, but you had to be careful to position the thin upper buttstock such that it was against the bicep, rather than tucked into your shoulder as with a modern style of gun. The lighter weight did make the recoil more noticeable.

Below that: Swedish Snaplock. .77 ball, 60gr FFg.  Very similar to the Caliver in how it felt, though the mechanism is a type of flintlock. The larger ball would have probably benefited from more powder (the rule of thumb is about 1gr of powder per point of caliber, to start with), but it still had no problems penetrating the 3/4″ plywood at about 15 yards.

Under the Snaplock are three small Pedersoli handguns:

1. Derringer Rider (Hardened). Uses just a #11 percussion cap to shoot a 4.5BB (standard .177 round ball). We couldn’t get this one to shoot — after the first shot, the BB was stuck in the barrel.
2. Derringer Guardian. Uses just a 209 primer to shoot a 4.5BB (standard .177 round ball).  This one shot fine, and was a fun little gun. Trying to hit anything at more than arm’s length was a challenge …
3. Derringer Liegi. This uses a percussion cap and 10gr of FFFg powder to shoot a .451 ball. The trigger is retracted until the hammer is drawn to full cock. This was actually a lot of fun to shoot, and had a respectable amount of power behind it. At about 5 yards it shot about a yard high from what you initially expected, but with a little practice …

Some pics of the Guardian and Liegi being shot:

To the right of the Pedersoli handguns is a Hand Mortar. This has a .75 chamber with a 2.5″ bore. Which, it so happens, is perfect for shooting a tennis ball …
Keith shot the first ball at our plywood target, using 75gr of FFg. The tennis ball bounced right back at us. So we reused it, this time increasing the load to 100gr of FFg, shooting it into an adjacent field. It lobbed about 60 yards. The last shot was with 120gr of FFg, and that sent the tennis ball 75+ yards. I expect that if you stuffed some wadding or such down into the .75 chamber, and tamped it appropriately, that you’d get much better performance. But we were laughing too much to think of trying that at the time.

Under the Mortar is a LeMat Cavalry revolver. The 9 chambers are .44, and we used a .451 ball with 40gr of FFFg for each. The center chamber can also shoot a 20ga shot load, but we decided not to fuss with that. We used the recommended #11 percussion caps, but #10 would have fit better. This gun was new, but the trigger was *extremely* hard to pull and cocking the hammer almost took two hands. It would probably benefit from a fluff & buff … but I don’t think I’ll run out to buy one to try it.

To the left of the LeMat is an Early Matchlock Arquebus.  .58 ball, 60gr FFg. Surprisingly easy to shoot, and reliable under the pleasant autumn conditions we had. All of us found it easy to hit close to point of aim, even with the significant delay you have with a matchlock.

Below that: a Kentucky Flintlock Rifle. .50 (we used a .490 ball) with 60gr of FFg. This is the iconic flintlock for most people, and felt & shot well. Though curiously, the delay from ignition of the pan to the rifle firing seemed long to me, compared to my Mortimer (see below).

Moving to the second image of guns at the top of the post …

Starting at the top, on the left side of the image: simple Hand Gonne in brass. .62 ball with 60gr Fg. After pouring in the powder, you just drop the ball in without a patch … and have to pay attention that you don’t let it roll out again. We started the day shooting this, and all had entirely too much fun. Initially we used 40gr of Fg, and were able to pick up and reuse the ball, since it just bounced off the plywood target.

Below the Hand Gonne is my 1815 Mortimer flintlock. .535 ball with 60-80gr of FFg. I’ve written about this gun previously for my personal blog, and really enjoy shooting it. Even with the more powerful loads, there’s very little recoil … because the damned thing weighes a ton! But it is well broken in, shoots very well, and is accurate in my hands to at least 100 yards.

Under that is my new 1858 Remington Revolving Carbine. .454 ball with 30gr of FFFg. This was my first outing with this gun, and I just love it. We all were able to shoot about 4″ groups at 15 yards the first time. With a little practice, I am sure I can extend that considerably. Here’s  a couple of images of it from this weekend:

And some video:

Under that is a French Blunderbuss. .735 ball with 60gr Fg. This was the first time any of us had shot one of these muskets, and we were all pleasantly surprised at how accurate and reliable it is. I can now understand why it was considered such a valuable weapon for close combat.

Next down is the Kentucky Percussion Rifle. .50 (we used a .490 ball) with 60gr of FFg. This is the twin to the iconic flintlock up above, and shot nearly identically … except that the #11 percussion cap gave immediate ignition to the charge. A very nice shooting rifle.

Next to last on the left side of the second image is a Japanese Matchlock. .50 (we used a .490 ball) with 60gr of FFg. I had shot this one previously, but it was fun to revisit it and compare it to the other matchlocks we had. All of us found it easy and accurate to shoot.

At the bottom on the left is a 1766 Charleville musket. .68 ball with 80 grains of FFg. This gun had probably the longest delay of any of the flintlocks we shot, but was still very fun to shoot, went off reliably, and seemed very accurate.

On the top of the right side of the second collection of guns is another 209 primer only 4.5BB carbine: the White Hawk. This was *surprisingly* fun to shoot! It was easy to use, accurate, and the .177 pellet seemed to hit with more authority than you would expect, though we didn’t test it for power. All of us had to try this several time. I could really see this being a fun little thing to shoot in your basement or some such.

Below the White Hawk is a Howdah Hunter: a twin-barrel .50 percussion cap gun which we loaded using a .490 ball with 30gr of FFFg. While heavy and with a stiff pair of triggers (one for each barrel), this was easy to shoot than I expected. Recoil wasn’t bad, and accuracy was good.

Under the Howdah, hidden (unintentionally) in the gun case, is a home-made Hakenbushe (hook gun), a variation on the early hand gonne which had a ‘handle’ that was a steel spike, used for close defensive work after the gun had been fired. This one shot a .735 ball with 60gr of FFg, and like the other hand gonne above, didn’t use a patch. So you had to make sure not to tilt the barrel down, or the ball and powder would roll out.

Under that is a classic Hawken rifle. .50 call (.490 ball) with 60gr of FFg. This may be more popular than even the Kentucky long rifle, and it was a fun old friend to revisit.

Lastly, two nice flintlock pistols, only one of which we were able to actually shoot. That was the 1763 Charleville pistol, .68 ball with 40gr FFg. A classic cavalry pistol which was very easy to shoot.

The remaining flintlock is a Murdock Scottish highland pistol .52 cal. Unfortunately this one needed to have the touch-hole reworked a bit. So perhaps we’ll get to shoot it next time …

Jim Downey

Special thanks to my friends and cohorts: Jim, Keith, and Roger. I appreciate you sharing your guns and knowledge, but most of all your friendship!

 

Velocity is great, but mass penetrates.

OK, kiddies, it’s time for SCIENCE!

Ballistic science, specifically. I promise to keep the math to a minimum, because I don’t like it much, either. Jim Kasper is the one who thinks in terms of equations, not me.

If you look at any of the various pages for test results on BBTI you will see that each caliber/cartridge also has a link for a Muzzle Energy (the kinetic energy of a bullet as it leaves the muzzle of a gun) graph for that set of results. That’s because Muzzle Energy can also give an idea of the effectiveness of a given ammo, since it is a calculation of both the weight of a bullet as well as the velocity it is traveling. This calculation, specifically:

Here’s what that says in English, taken from the explanation that goes with that image on Wikipedia:

The kinetic energy is equal to 1/2 the product of the mass and the square of the speed.

In other words, you multiply the weight of the bullet times the square of the velocity, then take half of whatever number you get. And that gives you the Muzzle Energy, usually (as on our site) expressed in foot-pounds of energy.

So there are two ways you can change the result: change the amount of weight, or change the amount of velocity.

But since it is the square of the velocity (the velocity times itself), changes to the velocity have a larger impact on the final amount of Muzzle Energy. That’s the reason why how the velocity changes due to barrel length is such a big deal, and why we’ve done all the research that we’ve done over the last seven years.

But while Muzzle Energy gives you a good way to compare the power and potential effectiveness of a given cartridge as a self-defense round, there are a couple of other factors to consider. A couple of VERY important factors.

One is the shape and composition of the bullet itself. There’s a very good (surprisingly good, in fact — I heartily recommend you read the whole thing) discussion of the basic shapes and how they interact with the human body in this online teaching tool intended for medical students. The relevant excerpt:

Designing a bullet for efficient transfer of energy to a particular target is not straightforward, for targets differ. To penetrate the thick hide and tough bone of an elephant, the bullet must be pointed, of small diameter, and durable enough to resist disintegration. However, such a bullet would penetrate most human tissues like a spear, doing little more damage than a knife wound. A bullet designed to damage human tissues would need some sort of “brakes” so that all the KE was transmitted to the target.

It is easier to design features that aid deceleration of a larger, slower moving bullet in tissues than a small, high velocity bullet. Such measures include shape modifications like round (round nose), flattened (wadcutter), or cupped (hollowpoint) bullet nose. Round nose bullets provide the least braking, are usually jacketed, and are useful mostly in low velocity handguns. The wadcutter design provides the most braking from shape alone, is not jacketed, and is used in low velocity handguns (often for target practice). A semi-wadcutter design is intermediate between the round nose and wadcutter and is useful at medium velocity. Hollowpoint bullet design facilitates turning the bullet “inside out” and flattening the front, referred to as “expansion.” Expansion reliably occurs only at velocities exceeding 1200 fps, so is suited only to the highest velocity handguns.

Now, while that last bit about needing to exceed 1200 fps may have been true, or a ‘good enough’ approximation a few years ago, it isn’t entirely true today. There has been a significant improvement in bullet design in the last two decades (and these innovations continue at a rapid pace), so that there are now plenty of handgun loads available which will reliably expand as intended in the velocity range expected from the round.

The other REALLY important consideration in bullet effectiveness is penetration. This is so important, in fact, that it is the major criteria used by the FBI and others in assessing performance. From Wikipedia:

According to Dr. Martin Fackler and the International Wound Ballistics Association (IWBA), between 12.5 and 14 inches (318 and 356 mm) of penetration in calibrated tissue simulant is optimal performance for a bullet which is meant to be used defensively, against a human adversary. They also believe that penetration is one of the most important factors when choosing a bullet (and that the number one factor is shot placement). If the bullet penetrates less than their guidelines, it is inadequate, and if it penetrates more, it is still satisfactory though not optimal. The FBI’s penetration requirement is very similar at 12 to 18 inches (305 to 457 mm).

A penetration depth of 12.5 to 14 inches (318 and 356 mm) may seem excessive, but a bullet sheds velocity—and crushes a narrower hole—as it penetrates deeper, while losing velocity, so the bullet might be crushing a very small amount of tissue (simulating an “ice pick” injury) during its last two or three inches of travel, giving only between 9.5 and 12 inches of effective wide-area penetration.

As noted above, the design of the bullet can have a substantial effect on how well it penetrates. But another big factor is the weight, or mass, of the bullet relative to its cross-section — this is called ‘sectional density‘. Simply put, a bullet with a large cross-section and high mass will penetrate more than a bullet with the same cross-section but low mass moving at the same speed. It isn’t penetration, but think of how hard a baseball hits versus a whiffleball moving at the same speed. They’re basically the same size, but the mass is what makes a big difference. (See also ‘ballistic coefficient‘).

With me so far?

OK, let’s go all the way back up to the top where I discussed Muzzle Energy. See the equation? Right. Let’s use the baseball/whiffleball analogy again. Let’s say that the baseball weighs 5.0 ounces, which is 2,187.5 grains. And the whiffleball weighs 2/3 of an ounce, or 291.8 grains. A pitcher can throw either ball at say 60 mph, which is 88 fps. That means (using this calculator) that the Kinetic Energy of a baseball when it leaves the pitcher’s hand is  37 foot-pounds, and the whiffleball is just 5 foot-pounds. Got that?

But let’s say that because it is so light, the pitcher can throw the wiffleball twice as fast as he can throw a baseball. That now boosts the Kinetic Energy of the whiffleball to 20 foot-pounds.

And if you triple the velocity of the whiffleball? That gives it a Kinetic Energy of 45 foot-pounds. Yeah, more than the baseball traveling at 88 fps.

OK then.

Now let’s go look at our most recent .45 ACP tests. And in particular, the Muzzle Energy graph for those tests:

What is the top line on that graph? Yeah, Liberty Civil Defense +P 78 gr JHP.  It has almost 861 foot-pounds of energy, which is more than any other round included in those tests. By the Muzzle Energy measure, this is clearly the superior round.

But would it penetrate enough?

Maybe. Brass Fetcher doesn’t list the Liberty Civil Defense +P 78 gr JHP. But they did test a 90 gr RBCD round, which penetrated to 12.0″ and only expanded by 0.269 square inch. Compare that to the other bullets listed on his page, and you’ll see that while the depth of penetration isn’t too bad when compared to other, heavier, bullets, that round is tied with one other for the least amount of expansion.

Driving a lightweight bullet much, much faster makes the Muzzle Energy look very impressive. Just the velocity of the Liberty Civil Defense +P 78 gr JHP is impressive — 1865 fps out of a 5″ barrel is at least 50% faster than any other round on our test results page, and almost 400 fps faster than even the hottest of the .45 Super loads tested.

But how well would it actually penetrate? Without formally testing it, we can’t say for sure. But I am skeptical. I’m not going to volunteer to getting shot with one of the things (or even hit with a whiffleball traveling 180 mph), but I’m also not going to rely on it to work as it has to in the real world, where deep penetration is critical. I want a bullet with enough punch to get through a light barrier, if necessary. Like this video from Hickok45, via The Firearm Blog:

Personally, I prefer a heavier bullet. Ideally, I want one which is also going to have a fair amount of velocity behind it (which is why I have adapted my .45s to handle the .45 Super). All things being equal (sectional density, bullet configuration and composition), velocity is great, but mass is what penetrates.

Jim Downey

The illusion of precision.

Got an email which is another aspect of the problem I wrote about recently. The author was asking that we get more fine-grained in our data, by making measurements of barrel lengths by one-eighth and one-quarter inch increments. Here’s a couple of relevant excerpts:

what more is really needed, is barrel lengths between 1-7/8 and 4-1/2″.
because of the proliferation of CCW and pocket pistols, and unresolved
questions about short barrel lengths that go all over between 2 and 3.75″,
and snubby revolvers that may be even shorter.

* * *

with that amount of precision, not only would you have data covering all
lengths of short barrels, but you could fabricate mathematical curves that
would predict velocities for any possible barrel length, metric or
otherwise, given the particular ammo.

 

It’s not an unreasonable thought, on the surface. Our data clearly shows that the largest gains in bullet velocity always come in length increases of very short barrels for all cartridges/calibers. So why not document the changes between, say, a 4.48″ barrel and a 4.01″ one? That’s the actual difference between a Glock 17 and a Glock 19, both very popular guns which are in 9mm. Or between a S&W Model 60 with a 2.125″ barrel and a S&W Model 360PD with a 1.875″ barrel?

Ideally, it’d be great to know whether that half or quarter inch difference was really worth it, when taking into consideration all the other factors in choosing a personal defense handgun.

The problem is that there are just too many different variables which factor into trying to get really reliable information on that scale.

Oh, if we wanted to, we could do these kinds of tests, and come up with some precise numbers, and publish those numbers. But it would be the illusion of precision, not actually useful data. That’s because of the limits of what we can accurately measure and trust, as well as the normal variations which occur in the manufacturing process … of the guns tested; of the ammunition used; of the chronograph doing the measurements; even, yes, changes in ambient temperature and barometric pressure.

That’s because while modern manufacturing is generally very, very good, nothing is perfect. Changes in tolerance in making barrels can lead to variation from one gun to the next. Changes in tolerance in measuring the amount of gunpowder which goes into each cartridge (as well as how tight the crimp is, or even tweaks in making the gunpowder itself) mean that no two batches of ammunition are exactly alike. And variations in making chronographs — from the sensors used, to slight differences in positioning, to glitches in the software which operate them — mean that your chronograph and mine might not agree on even the velocity of a bullet they both measure.

All of those little variations add up. Sometimes they will compound a problem in measuring. Sometimes they will cancel one another out. But there’s no way to know which it is.

This is why we’ve always said to consider our data as being indicative, not definitive. Use it to get a general idea of where your given choice of firearm will perform in terms of bullet velocity. Take a look at general performance you can expect from a brand or line of ammunition. Compare how this or that particular cartridge/caliber does versus another one you are considering.

But keep in mind that there’s no one perfect combination. You’re always going to be trading off a bunch of different factors in choosing a self-defense tool.

And never, ever forget that what matters most — FAR AND ABOVE your choice of gun or ammunition — is whether or not you can use your firearm accurately and reliably when you need to. Practice and training matters much more than whether or not you get an extra 25, or 100, or even 500 fps velocity out of whatever bullet is traveling downrange. Because if you can’t reliably hit your target under stress, no amount of muzzle energy is going to do you a damn bit of good.

 

Jim Downey

If you want more information about how accuracy and precision can be problematic, this Wikipedia entry is a good place to start.

Do you want good data, or useable data?

Got a question I haven’t seen for a while. Here it is, with my answer (and a little bit of additional explanation) to follow:

Thanks for the site!  You do not post the altitude and  temperature of your results (unless I missed that).  Can you let us know what your reference points are?  Also, what effect would altitude and temperature variation have on your results?

Here’s the answer I gave:

Well, it’s been a while since anyone asked about that … thanks!

We did discuss this early on, and decided pretty quickly that while both of those would indeed have an effect (as would the changes in barometric pressure), that it would be so small as to not matter for the degree of accuracy of our testing equipment and the limited number of rounds tested. If you were trying to get really good data, everything would have to be much more rigorous and controlled … and we would never ever have gotten the data that we did. So as I remind people: consider the results to be *indicative*, not definitive. In other words, don’t try to read too much into variances of a few feet-per-second, or convince yourself that such minor differences really matter.

Hope that helps to give a little perspective.

Oh, and I can answer one of your questions: almost all the testing was done at an elevation of approximately 744′ above sea level, according to commercial GPS systems.

I think that’s pretty clear, but I want to emphasize one part of it: that if we had set out to provide really rigorous and statistically-significant data, the chances are that we would never have even gotten past the first test sequence. And that means there would be NO BBTI.

As it is, we have tested something in excess of 25,000 rounds over the last 7 years. At a personal cost of more than $50,000. And that doesn’t begin to include the amount of labor which has gone into the project. To get really solid data which was statistically significant, we probably would have needed to do at LEAST three or four times as many rounds fired. With three or four times the amount of time testing. And crunching the data. And cost out of pocket.

Which would have meant that we probably would never have gotten through a single test sequence.

So it’s a matter of perspective. Do you want some data which is reasonably solid, and gives a pretty good idea of what is going on with different cartridges over different barrel lengths? Or do you want very accurate, high rigorous data which would never have been produced?

Hmm … let me think about that … 😉

 

Jim Downey

PS: We haven’t forgotten about the .45 Super/.450 SMC tests — it’s just been a busy summer. Look for it soon.

Perceived recoil and bullet weight.

Got a great question recently, and I thought I would share some of my thoughts about it, then invite others to weigh in. Here’s the question:

I hope that you folks can help me with a question I have had for many years now. Why is the recoil so much heavier with lighter bullets in the same caliber and powder loadings than heavier bullets of the same caliber and loadings?

For example. With my S&W model 60, Gold Dot L/E 38 special 135 grain JHP +P loads recoil much harder than the Remington 125 grain JHP +P loads. The same thing happens with my Glock mod 23 .40cal when I shoot 180 grain JHP rounds vs 165 grain JHP rounds. The 165 grain rounds recoil much harder. One would think the heavier round with the same powder load would recoil harder. Can you help?

Perceived recoil is a surprisingly complex problem. It’s not just a matter of total force, but the ‘shape’ of the recoil impulse as well. Then there are the ergonomics of how a particular gun fits a particular person/hand. Add in the mechanical action of how the gun operates (some use part of the recoil energy to cycle the action, some don’t), and various psychological/physiological factors (are you tired? just had an adrenaline dump? afraid of a given gun/caliber/cartridge?), and you can see how many different factors might come into play.

A good place to start is to look at the equation for Muzzle Energy (ME). Let’s use the numbers for the Steyr M40 (very similar to your Glock 23) which was one of the ‘real world’ guns used in the .40 S&W tests we did. Calculations are from Airhog.

The 165gr Federal Hydra-Shok JHP has a velocity of 943fps out of the 4″ barrel. That gives a Muzzle Energy of 325.88ft-lbs.
The 180gr Federal Hydra-Shok JHP has a velocity of 989fps out of the 4″ barrel. That gives a Muzzle Energy of 391.04ft-lbs.

OK, that would seem to indicate that the heavier bullet should cause more recoil. The ME is higher, and you’re shooting them out of the same gun.

But I’m a little wary of that example. Usually, a lighter bullet is faster than a heavier one if they have the similar powder charge, out of barrels of the same length. Here’s another example, looking at 9mm from a Beretta 92.

The Cor-Bon 90gr JHP +P has a velocity of 1522 out of the 4.875″ barrel. That gives a Muzzle Energy of 463.05ft-lbs.
The Cor-Bon 125gr JHP +P has a velocity of 1291 out of the 4.875″ barrel. That gives a Muzzle Energy of 462.72ft-lbs.

And those are very close to the same amount of ME, and should feel about the same in terms of recoil were that the only factor.

So what’s going on? Why do we see one instance where the ammo is just a bit faster in the heavier bullet (resulting in higher ME), but much slower in another instance?

I suspect that it’s probably due to differences in loadings between the different ammo. Even with ammo from the same manufacturer (in the examples above), there’s nothing saying that they are using either the same propellant OR similar amounts of the same propellant for loadings which use different bullet weights. That means that trying to generalize the amount of recoil between different bullet weights just on the basis of brand is difficult if not impossible.

Furthermore, if you’ve done any reloading, or spend some time looking over reloading data, you’ll know that even when you’re using the same propellant in the same cases, different bullet weights usually means different bullets (in terms of manufacturer and/or shape) resulting in different seating depths and overall length. It may seem to be a trivial matter, but this results in different pressure profiles (the amount of pressure within the firing chamber of the gun). Just one example, taken from the Hodgdon Reloading site, for maximum-pressure loads using  GDHPs:

The 90gr bullet with 7.0gr of Longshot powder has an overall length of 1.010″ and gives a velocity of 1,378fps, a pressure of 32,300 PSI, and would have a ME of 379.57ft-lbs.
The 115gr bullet with 6.0gr of Longshot powder has an overall length of 1.125″ and gives a velocity of 1,203fps, a pressure of 32,300 PSI and would have a ME of 369.64ft-lbs.

Note that while the heavier bullet uses a full 1.0gr less of propellant and has a longer overall length, it generates the same amount of pressure. If we drop back to the same amount of the same powder for each loading (6.0gr), then the pressure generated in the lighter bullet loading drops to 29,400 PSI, velocity drops to 1,278fps, and ME drops to 326.48ft-lbs.

But not all pressure is created equal, even if it is nominally ‘the same’. The pressure impulse also matters. That’s the curve of how the pressure rises and falls over time, which is largely related to how ‘fast’ or ‘slow’ the propellant burns. Propellants used for handgun loads tend to be very ‘fast’ (burn rapidly), so the impulse tends to be sharper.  Here’s a good explanation of the matter.

And if you think about it, the heavier the bullet used, the longer/slower it takes to start moving when the cartridge is fired. That should mean that the impulse is spread out over a slightly longer time than it would be with a lighter bullet. So in some sense, the lighter bullet would result with a ‘snappier’ feel. And that may well be what it is that you’re feeling when you experience more perceived recoil (and have controlled for all the other factors) from lighter bullets.

Other thoughts on the subject?

 

Jim Downey

 

 

 

 

Confirmation of the .460 Rowland performance.

John Ervin at Brass Fetcher Ballistic Testing has just put up a new page about his testing of the .460 Rowland cartridge. As I have explained in the past,  our work at BBTI is intended to be an overview of how ballistic performance varies over barrel length — it is just a quick survey to get an idea of the general trends, not meant to be an in-depth examination of a specific cartridge.

But in-depth testing is exactly what Ervin does, using a larger sample size, ballistic gelatin, and high-speed videography. And as a result, his much more detailed analysis is more useful for getting into the details of a given cartridge out of a specific barrel length. And it is really good to see that his results confirm what I have been saying all along: that if you carry a .45, you should instead be carrying a .460 Rowland.

What specifics? Take a look at the performance of Speer 230gr Gold Dot HP .45ACP in terms of foot-pounds of kinetic energy transfer into 20% ballistic gel:

 

Pretty good, eh? It’s what we expect from the .45ACP: a solid energy dump and reasonable penetration.

Now let’s take a look at the same chart, but with the Speer 230gr Gold Dot HP in .460Rowland:

The curves don’t look that different on first glance, but pay close attention to the scale there on the left axis of each one: where the .45ACP tops out at about 72 ft/lbs about 2″ into the gel, the .460Rowland tops out at about 335 ft/lbs just before 2″. That’s more than 4x the energy transfer.

In fact, at 5″ of penetration, the .460Rowland is still dumping about as much energy as the .45ACP does at the maximum.

But there’s more than simple energy transfer involved in terminal ballistic performance. There’s also how well the bullet is designed, and whether it expands properly. This can be a big concern in “over-driving” a bullet, so that it breaks apart. Well, Ervin’s data also covers these comparisons quite well. For the two specific rounds cited above, the .45ACP expanded to 0.344 square inches of frontal surface, and was still 229.5gr of weight. And the .460Rowland expanded to 0.526 square inches of frontal surface, and was still 221.3gr of weight.

There’s a *LOT* more information at Brass Fetcher Ballistic Testing. Ervin has an extensive 17 page Ammunition Performance Data report in .pdf format which contains a ton of images, video, and data — more than enough to keep even a data-junkie like me busy for a long time. I urge you to take a good look at it, and to consider the thoughts which Ervin shares about this cartridge. But I will leave you with his opening sentence which sums it up very nicely:

The 460 Rowland represents the pinnacle of handgun calibers for self-defense.

 

Agreed.

Jim Downey

June? Already?

Yeah, seems to be. So here’s the numbers & info for the last month, plus a little look ahead:

We had 19,937 visitors to the BBTI homepage in May. We’ve added a number of additional review links to the list of Real World Guns. Followers for both Twitter and Facebook have also seen a nice uptick this last month.

Back in March I reported on how Google Adsense had screwed us over. Well, after looking at a number of options and being realistic about what kind of revenue advertising could generate, we’ve pretty much decided to just give up on advertising — with one small exception for now: you’ll note that some of the BBTI pages have a small ad promotion my novel. It is proving to be very popular, and the reviews for it have been quite positive — check it out. Of course, we’re still happy to accept donations to help offset expenses associated with BBTI — and thanks to those who have donated!

Happy & safe shooting, everyone!

Jim Downey