Ballistics by the inch

2016 in the rear-view mirror.

Happy New Year!

A quick recap of the last year: surprisingly active.

It’s interesting to see how things have evolved with BBTI over time. The last test sequence we did was the .45 Super /.450 SMC tests, with the data published in October 2015. So without new test results last year, we didn’t have the usual big spike in site visits. But we still saw a total of 447,203 visitors last year, which ain’t too shabby.

And last year we saw an evolution in who were our biggest referrers, as well. Excluding search engines, here they are in order:

  3. MechTech Systems
  4. Wikipedia
  5. The Firearm Blog
  6. reddit
  7. Active Response Training
  8. Survivalist Boards
  9. The Firing Line

All but four (, MechTech Systems, Wikipedia, and The Firearm Blog) are discussion forums, and of those four The Firearm Blog also has a very active discussion community. MechTech Systems sells conversion kits for pistols, allowing you to turn your pistol into a carbine, so it makes perfect sense that they would link to us showing the advantage you can gain with a longer barrel.

In other words, most of the referrers are places where BBTI is being cited as a reference to help people make decisions about their firearm choices. That just makes sense, and corresponds to the email we get, thanking us for our site or asking for clarification/recommending new ammo to test. After 8 years, and with no new tests, there’s not much reason for the ‘news’ sites to mention us — but there’s still plenty of interest in the firearms community in the data we provide.

So thanks to all who share our site with others! You’re the real reason our site is a success!


Jim Downey


January 1, 2017 Posted by | .45 Super, .450 SMC, Data, Discussion., Links | , , , , , , , , , , , , , , , , , , , , , | Leave a comment

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:

E_\text{k} =\tfrac{1}{2} mv^2

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

November 8, 2015 Posted by | .45 ACP, Data, Discussion. | , , , , , , , , , , , , , , , , , , , , , , , , , , , | 3 Comments

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.

September 6, 2015 Posted by | .357 Magnum, .38 Special, 9mm Luger (9x19), Data, Discussion., General Procedures | , , , , , , , , , , , , , , , , | 2 Comments

No matter which way you look …

…whether back over 2014, or forward into 2015, things are pretty good vis-a-vis BBTI.

Yeah, 2014 was pretty good. We didn’t do any formal testing, though I did some informal testing and a fair number of reviews of new guns or guns which were just new to me.  Having the chance to do those now and again is enjoyable, without having the same deadline pressures I had when I was doing regular columns and reviews for

The numbers also look pretty good for 2014. This blog went from about 12,000 visits in 2013 to 22,000 last year – nearly double. And the BBTI site itself jumped from 243,230 visitors in 2013 to 318,304 visitors in 2014 — an increase of about a third. Visits have also continued to climb pretty steadily from day-to-day, with typically about 1,250 or so daily by the end of the year. Given that we didn’t do any new testing, that’s pretty impressive.

And of course, we’d like to thank all who linked to us over the past year. Here’s the top ten referring sites for 2014, excluding search engines and Wikipedia:


How about the year to come, then?

Well, we’re planning on doing one largish series of tests, to cover .45 Super, .450 SMC, and a number of additional .45 ACP loadings. We haven’t yet set a date for this sequence, but I will post a note about it here and on our Facebook page once plans solidify.

And behind the scenes, improvements continue at the BBTI website. We recently upgraded our hosting set-up, to shift over to more modern software technology. We’ve started discussing how we can do better presentations of our graphs and spreadsheets. I would still very much like to work with someone to develop a mobile app — if you have the necessary skill set to do that, please drop me a note. And whenever someone finds a glitch in our data or how the site renders for them, we try and make the corrections. None of this is very obvious, but it is all a lot of work, and I’d like to once again thank our web guru (and my lovely wife) at Coeurbois Graphic Design for her efforts.

Lastly, thanks to all who use the site regularly, who cite us in online discussions, who help to spread the word. And especially, I would like to thank all who have donated to BBTI in the last year — your tangible contributions make a difference, and help to offset our ongoing costs.

Happy New Year!


Jim Downey

January 2, 2015 Posted by | .45 ACP, .45 Super, .450 SMC, Boberg Arms, Data, Discussion., Links | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , | 1 Comment