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 Guns.com, and it originally ran 2/9/2011. Some additional observations at the end.

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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.

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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

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

Pump it up.

Last weekend I had the chance to revisit a couple of old friends, and try out something new: pump rifles. These guys:

PumpsFrom top to bottom:

 

If you check those links, you’ll see that I have written formal reviews for both the Uberti and the USFA previously. So I won’t spend much time talking about them.

But the little Taurus deserves a quick review. Because I found it to be a *very* nice little pump gun. The action was slick and didn’t have any problems, even though it was basically brand new. The Buckhorn sights are classic for a reason: they’re intuitive and work very well at modest distances. And even though the gun is relatively lightweight (compare the neck of the stock to the other two pump rifles above), there’s more than enough mass there to tame the recoil from the .22magnum cartridge. That means that you can get very quick and tight groups out of it even just standing and shooting it unsupported. Shooting it is just a blast, though one which doesn’t come with a lot of muzzle flash.

And the wood & finish on this gun is surprisingly good:

Taurus pump

 

I also want to share a couple of detail pics of the engraving on the USFA:

Engraving

And the other side:

Engraving2

Very nice!

I *do* like pump guns.

 

Jim Downey

 

November 22, 2014 Posted by | .22WMR, .357 Magnum, .38 Special, .45 Colt | , , , , , , , , , , , , , , , | Leave a comment