Ballistics by the inch

Reprise: Ammo by the Numbers: What Do All Those Numbers on My Box of Ammo Mean?

My friends over at the Liberal Gun Club asked if they could have my BBTI blog entries cross-posted on their site. I said yes, and got to thinking that perhaps I would revisit 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 the first article I wrote for, and it originally ran 2/9/2011. Some additional observations at the end.


One of the most bewildering moments for a relatively novice shooter is selecting ammunition. Go online, or into a big-box store, or even into your local gun shop and you can be confronted with a huge array of choices in any given caliber or cartridge design. Most of the boxes have a sort of ‘code’ on the side; some have little charts or even graphs on the bottom. But which one do you want? What does this stuff even mean? Do claims of a certain velocity or energy tell you anything?

Let’s take a look at some terms, first.

Most prominently displayed figure on the box, is the cartridge: .45 Auto, .357 Magnum, 9mm Luger and so forth. There can be some confusion on this, so be sure to check your gun to see what it says on the side of the barrel or slide, or is specified in the owner’s manual  – that’s the only kind of ammunition you want. There is a difference between a .45 Colt and a .45 Auto, or a .357 Magnum and a .357 Sig, just for a couple of examples – make sure you get the kind of cartridge that your gun handles. It may seem silly to bring this up, but even experienced shooters can accidentally grab the wrong box of ammo sometimes – I have made this very mistake myself.

Next you’ll find a number, listed with either “grain” or just “gr.” This tells you the weight of the actual bullet.

Then there will be some variety of description of the bullet, indicating intended use. It could say “target” or “range” or just “ball” – all of these mean a basic bullet, probably with a slightly rounded nose, or perhaps a conical shape, or just a simple cylinder which might also have a small flat conical front (sometimes called a semiwadcutter or “SWC”). The actual bullet may be just lead or may have a “full metal jacket” – a thin layer of some harder metal such as a copper alloy. “Hunting” usually means a “JSP” – jacketed soft point. “Self-defense” usually indicates some variety of “JHP” – jacketed hollow point. Some premium self-defense ammunition uses proprietary terms such as “DPX,” “Hydra-Shok,” and “GDHP” but these are largely marketing terms you don’t need to worry about too much, at least at first.

Terms “+P” or “+P+” indicate that the cartridge is somewhat more powerful (“over-pressure”) than standard for that cartridge. Most modern guns can handle a limited diet of such cartridges, but older guns may not. If in doubt, check your gun’s owner’s manual or ask a gunsmith.

Particularly on premium defensive ammunition you may see some indication of the “velocity” or “energy” of the cartridge. Here in the US, velocity is given in “fps” – feet per second. “Energy” is given in “ft/lbs” – foot-pounds (the amount of energy needed to lift one pound one foot off the ground, not the confusingly similar term used to measure torque). The faster a bullet, and the more it weighs, the more kinetic energy it has. Sometimes a little chart will be given, showing velocity and energy at the muzzle of the gun, then at one or more distances (bullets lose velocity and energy due to air resistance).

While more velocity and more energy are generally good things for defensive ammunition, don’t get too hung up on these numbers. Why? Because the manufacturers don’t really give you enough information to compare one ammunition to another one easily. They don’t tell you what the barrel length used was (and this can have a huge impact on velocity). They don’t tell you the type of gun used (a revolver and a semi-auto both have different effects on the speed of a bullet). And they don’t tell you the type of barrel used (some barrels are known to be ‘faster’ than others.)

Then why bother at all with this information? Because it can help in some instances. If all you’re going to do is just use your gun for ‘plinking’, you can probably get whatever ammunition is cheapest and suitable for your gun.

But if you’re after accurate and consistent target shooting, or use your gun for hunting or defensive purposes, you want to be choosy. Once you find ammunition you and your gun like, you want to try to stay as close to that ammunition as you can. What do I mean by ammunition you and your gun like?

Some guns will feed and fire some ammunition better than others. The shape of the bullet can make a difference. The weight of the bullet can make a difference. The amount of energy can make a difference.

Ammunition with greater energy will cause your gun to have greater recoil (‘kick’), and that can make it more difficult to shoot. Ammunition which is touted for being “reduced recoil” likely has less energy than other ammunition, that can make it less effective for hunting or self-defense.

Using the same amount of gunpowder, a lighter bullet will go faster than a heavier one. But a heavier bullet will generally slow down less due to air resistance, and will generally penetrate deeper into whatever you are shooting at.

“Target,” “ball,” and similarly-termed ammo is usually less expensive, and is good for practice. It is less ideal for self-defense purposes, because the bullet does not expand the way a hollow point or “JHP” is designed to when it hits flesh. “Hunting” ammunition is usually designed to expand some, but to still penetrate deeply.

Where should you begin?  Start out seeing what ammunition others who own a gun like yours use. None of your buddies shooting a gun like yours?  Maybe do a little checking online – many firearms forums post anecdotal information showing testing members have done, and there are some good sites that do more rigorous testing for velocity and penetration. See what is recommended, and give it a try.

So, beyond the numbers, what’s a good general rule when pairing ammo with a gun?  I’m of the opinion that, ideally, you should try out a box or two of different types of premium ammunition first to see which brands and type your gun likes. Using this as your guide, you can then launch the search for less expensive practice ammunition that is similar in weight and velocity, because that will behave similarly to your premium ammo in terms of point-of-impact and felt recoil.


Since I wrote this six years ago, there have been some noticeable changes in the ammunition industry, and now most manufacturers provide at least some basic information as to how the numbers they use were gathered — what barrel length, sometimes what gun they used — to make it a little easier for a consumer to know what they are buying. I have been told directly by some engineers and sales people at different companies that this is due to BBTI‘s testing and publication of our data, which has forced manufacturers to be more forthcoming.

Something else we’ve experienced in the intervening years was the Great Ammo Shortage (which for the most part has now passed). But it taught the wisdom of always keeping a bit more ammo on hand than you might otherwise need for a single trip to the range, to help ride out similar shortages in the future. I’ll address ammo storage issues in a future blog post.

Jim Downey

March 14, 2017 Posted by | .357 Magnum, .357 SIG, .45 ACP, .45 Colt, 9mm Luger (9x19), Data, Discussion. | , , , , , , , , , , , , , , , , , | 1 Comment

Comparison shopping.

Remember this graph comparing Muzzle Energy (ME)?



Well, a discussion elsewhere got me to thinking …

So, let’s take a look at .45 Super:



See what I see? Yeah, at 3″ and 4″ all the .45 Super loads are superior in terms of ME over all the other cartridges in the top graph. At 5″ the .357 Mag catches up with some of the .45 Super loads, and at 6″ it is in the center of the pack.

To really do the comparison right, I’d need to average all the .45 Super loads, then add them directly to the first graph, but that’s more time and trouble than I want to take. But my point is that of all the ‘conventional’ CCW-caliber/size guns, it looks like the .45 Super is at the top of the pile. We did formal testing of just one .460 Rowland, and it is comparable to the .45 Super at those barrel lengths (though I know from informal testing that some other loads are more powerful). You have to step up to full .44 Mag to beat either the .357 Mag or .45 Super.


Jim Downey

December 26, 2016 Posted by | .357 Magnum, .357 SIG, .380 ACP, .44 Magnum, .45 ACP, .45 Super, .460 Rowland, 10mm, 9mm Luger (9x19), Data, Discussion. | , , , , , , , , , , , , , , , , , , , , | Leave a comment

Join the party.

All along, we’ve said that if someone wanted to take the time, trouble, and expense to do some additional research along the lines of our protocols, that we’d be happy to include their data on our site. This is particularly true if it helped expand the selection of “real world guns” associated with the data for a given caliber/cartridge. Well, for the first time someone has expressed an interest in doing just that, prompting us to come up with an outline of what standards we feel are required for making sure it relates to our previous tests.

The biggest problem is that ammo manufacturers may, and do, change the performance of their products from time to time. This is why we have on occasion revisited certain cartridges, doing full formal chop tests in order to check how specific lines of ammo have changed. That gives us a benchmark to compare other ammo after a period of several years have passed, and shows how new tests relate to the old data.

But without going to such an extent, how can we be reasonably sure that new data collected by others using their own firearms is useful in comparison to our published data?

After some discussion, we feel that so long as any new testing includes three or more of the specific types of ammo (same manufacturer, same bullet weight & design) we had tested previously, then that will give enough of a benchmark for fair comparison. (Obviously, in instances where we didn’t test that many different types of ammo in a given cartridge, adjustments would need to be made). With that in mind, here are the protocols we would require in order to include new data on our site (with full credit to the persons conducting the tests, of course):

  1. Full description and images of the test platform (firearm) used in the tests. This must specify the make, model number, barrel length, and condition of the firearm. Ideally, it will also include the age of the firearm.
  2. That a good commercial chronograph be used. Brand isn’t critical — there seems to be sufficient consistency between different models that this isn’t a concern. However, the brand and model should be noted.
  3. Chronographs must be positioned approximately 15 feet in front of the muzzle of the firearm used to test the ammo. This is what we started with in our tests, and have maintained as our standard through all the tests.
  4. That five or six data points be collected for each type of ammo tested. This can be done the way we did it, shooting three shots through two different chronographs, or by shooting six shots through one chronograph.
  5. All data must be documented with images of the raw data sheets. Feel free to use the same template we used in our tests, or come up with your own.
  6. Images of each actual box of ammo used in the test must be provided, which show the brand, caliber/cartridge, and bullet weight. Also including manufacturer’s lot number would be preferred, but isn’t always possible.
  7. A note about weather conditions at the time of the test and approximate elevation of the test site above sea level should be included.

We hope that this will allow others to help contribute to our published data, while still maintaining confidence in the *value* of that data. Please, if you are interested in conducting your own tests, contact us in advance just so we can go over any questions.


Jim Downey

September 9, 2016 Posted by | .22, .223, .22WMR, .25 ACP, .30 carbine, .32 ACP, .32 H&R, .327 Federal Magnum, .357 Magnum, .357 SIG, .38 Special, .380 ACP, .40 S&W, .41 Magnum, .44 Magnum, .44 Special, .45 ACP, .45 Colt, .45 Super, .450 SMC, .460 Rowland, 10mm, 9mm Luger (9x19), 9mm Mak, 9mm Ultra, Anecdotes, Data, Discussion., General Procedures | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , | Leave a comment

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

First date with the Boberg XR9-S.

As I noted a couple of weeks ago, I picked up a ‘little brother‘ for my Boberg XR45-S. Here they are again:

Lil brother

Well, we’re having another delightful warm spell here in mid-Missouri, so yesterday afternoon I took advantage of it and went out to the range to give the little guy a try.

As I noted before, I have actually shot this particular gun a couple of times previously, and just loved it. But it had been a while, and I couldn’t remember specifically what ammo types we had used. So I packed up what variety of 9mm loads I had on hand, along with my chrono, and went to see whether anything had changed.

Because of the way they operate, the Boberg pistols have a tendency to be very particular about what ammo they like. Ammo which doesn’t have a sufficient crimp is prone to separate (the case being jerked away from the bullet). It’s an issue which is well known, and there’s a list of compatible ammo for both the XR9 and the XR45. But while those crowd-sourced lists are useful, the final word is always what specific ammo your particular gun will handle. For me, that’s particularly something I want to determine for any self-defense pistol before I will carry it.

Full details to follow, but for those who just want the short version: oh baby! The XR9 ate everything I fed it without a problem. Including my standard 9mm reloads. No mis-feeds. No bullet separation. No problems. And it was a real joy to shoot, which isn’t something I normally say about a pocket pistol handling full-power SD loads.

OK, for those want the details …

Below are informal* chrono numbers for seven different ammo types I had. These are all for the Boberg. But I also ran a few through my Steyr S9 for comparison, which usually just had an advantage of about 10 fps over the Boberg (the barrel on the Steyr is about a quarter of an inch longer). If that much.

  • Buffalo Bore 124gr JHP +P+                                             1,230 fps
  • Federal 124gr Hydra Shok JHP                                           1,025 fps
  • Reloads. (4.4gr HP-38, 124gr Rainier FMJ bullet)                        1,020 fps
  • Remington 124gr FMJ                                                       1,040 fps
  • Speer GDHP 115gr JHP                                                      1,210 fps
  • Speer GDHP 124gr JHP                                                      1,100 fps
  • Speer GDHP 124gr JHP +P ‘Short barrel’                           1,150 fps

As you can see, all pretty respectable numbers. And in keeping with both the claims of the manufacturer as well as what we had tested previously (where there’s overlap). I wouldn’t have any qualms carrying any of the Speer ammo, but my preferred SD ammo is currently the Buffalo Bore. Happily, the Boberg shot all of them without a glitch. And after getting my chrono numbers, I ran several magazines worth through the gun doing some quick shooting at cans, was getting excellent accuracy from it at about 15 yards.

I brought it home, stripped and cleaned it, and now consider it reliable enough to carry. Of course, I will continue to practice with it regularly, and keep a close on on how it performs with my reloads, and occasionally run a mag of carry ammo through it, but I don’t expect any problems. It’s a nice little gun.

Jim Downey

*By ‘informal’, I mean just using one chrono and without the lighting rig we now use for formal testing. And I would just run a magazine of ammo through, mentally noting the numbers in a running tally, then writing them down for that particular ammo, so they are necessarily just ‘ballpark’ figures. But since they jibe well with our previous numbers and what the mfg claims (which I only discovered when I sat down to write this), I think they’re pretty good.

January 20, 2015 Posted by | 9mm Luger (9x19), Boberg Arms, Data, Discussion. | , , , , , , , , , , , , , , , , , , , , , | 1 Comment

Boberg XR9-S: a new little brother for my XR45-S.

As Frank said on Facebook this afternoon:

I knew when you got the 45 you wanted the 9mm too. It was only a matter of time.

Guilty as charged. Look what followed me home today:

Lil brother

Yup, a Boberg XR9-S: a new little brother for my XR45-S. As I did in that post, I thought I’d put up some comparison pix to give a sense of just how small this gun is, even though it really doesn’t feel like it when you hold it or shoot it.

Here it is again with the XR45:

Lil brother 2

And here’s the view that shows the thickness of both:


Yeah, there’s a difference. Here’s the XR9 with a Springfield EMP (also 9mm, 3″ barrel – the XR9 has a 3.35″ barrel):



And with my J-frame in .38 Special:

W J-frame

For grins, here it is on top of the J-frame:

J Top

OK, but how about in comparison to the classic premium pocket 9mm, the Rohrbaugh R9? Here ya go:

W R9

The R9 *is* a fantastic little gun, and I love it. I don’t love shooting it, though. The XR9 wins in that category. It will also handle +P ammo and holds one more round (7+1) than the Rohrbaugh. But it is a bit bigger:

R9 Top

Lastly, here it is with a Bond Arms derringer — a great little gun, with a variety of different barrels available. But there’s still just two shots in the derringer, and it actually weighs about 3 ounces more.

W Bond

While I have shot this gun (it belonged to a good friend), and know it to be dependable, I do still want to make sure that it will be able to reliably digest my preferred SD loads. So more on that to come!


Jim Downey

December 26, 2014 Posted by | .45 ACP, .45 Super, 9mm Luger (9x19), Boberg Arms, Discussion. | , , , , , , , , , , , , , , , , , , , , , , | 1 Comment

With charts! Graphs! Slo-mo!

John Ervin at Brass Fetcher Ballistic Testing has put together another great video presentation, showing in several ways how Jacketed Hollow Point (JHP) ammo performs in comparison to Full Metal Jacket (FMJ) ammo for 9 different handgun cartridges. It’s long (22 minutes), but very nicely documents just exactly how the two different bullet styles behave at handgun velocities. Here’s the video:



The cartridges covered are .22 LR, .25 ACP, .32 ACP, .380 ACP, 9mm Makarov (9×18), 9mm Police (Ultra), .38 Special, 9mm Luger (9×19), and .45 ACP.  His data and presentation makes a great companion to our own data, and I really recommend that you set aside the time to watch the video at your earliest convenience.


Jim Downey

October 22, 2013 Posted by | .22, .25 ACP, .32 ACP, .38 Special, .380 ACP, .45 ACP, 9mm Luger (9x19), 9mm Mak, 9mm Ultra, Data, Discussion., Links | , , , , , , , , , , , , , , , , , , , , , | Leave a comment