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Command Performance: a test of modern bullet construction reveals how good today's slugs really ARE.

In all the press the FBI ballistic tests have gotten recently, one thing stands out: Today's bullets expand reliably, whereas that wasn't always the case. Back in the day, bullets were made by the cup-and-core method. The bullet manufacturer would stamp out little copper/brass cups, then hammer precut sections of lead wire into the cups. A few forming operations later--steps that give a particular curve to the nose, punch in any hollow point, possibly press a cannelure around the waist and then usually a final sizing--you'd have a finished bullet.

Copper and lead spring back from being bent, but they spring back by different amounts. If the last operation on a bullet is to force it through a die to make it round and the correct diameter, the lead gets squeezed but does not spring back as much as the copper does. This could--and did, in some cases--lead to a loose core-to-jacket fit. So a good bullet maker would make sure the last operation on a bullet was to press the core back in while holding the jacket in a sizing die or ring to keep it to correct diameter.

In this method, there is nothing holding the cup and core together but friction, and a bullet constructed in such a manner may or may not expand. If it does not reach its expansion velocity threshold, it will act like a full-metal-jacket projectile. Barriers also collapse the hollow point, making it an FMJ as well.

Once past the expansion velocity threshold, it will expand, and the faster it is going, the more it expands. And the expansion continues as velocity goes up, right up to the point where the bullet simply comes apart. All this time, as expansion increases, penetration decreases. And then, when the bullet is going fast enough that it breaks apart (or the core separates) then penetration becomes but a fond memory.

So in the days when traditional bullet construction was the primary method, ammo makers had to ensure they had enough speed to start expansion but not so much that they decreased penetration--and certainly not so much that the bullet just gave up the ghost. This was a difficult thing to accomplish with the original cup-and-core construction.

Today, things are so much different you'd hardly believe we are using the same calibers. In fact, the improvements in bullet construction have been so great, bullet makers can choose what level of performance they wish to deliver.

Case in point: Hornady Critical Defense and Z-Max ammo. The loads employ similar components, the major difference being the nickeled case used for the Critical Defense load and the different colors on the FTX bullet's polymer tip (red for Critical Defense, green for Z-Max).

Both loads nominally generate 1,140 fps for a 115-grain 9mm, and since I happened to have a good supply of the Z-Max on hand, I took the opportunity to do some testing in ballistic gelatin from pistols of various barrel lengths. This introduced a velocity variable, but not a bullet variable, into a ballistic inquiry. Why would I bother with this? Because handgun bullets designed in the post-FBI test era behave much differently than older ones do. First off, the velocity threshold for expansion is lower. Where we'd have to make sure almost all bullets were well over 1,000 fps to have any hope at all of expansion, now we can see them expanding well below that.

Second, and more surprisingly, you do not trade expansion for penetration. In fact, you get more of both. A post-FBI-standards bullet, driven faster, penetrates more even as it expands more.

I talked with Hornady's Dave Emary at length about this. He explained that the core/jacket bonding--either chemical or mechanical--is so good on modern bullets that more speed does expand the bullet, but the expansion does not decrease penetration, at least not at the rate it did in the old days.

As speed goes up, both penetration and expansion go up, to a peak. This peak velocity is different for each bullet, but it's typically faster than the normal velocity for a given caliber, even at +P velocities.

Once past the peak, penetration decreases as the bullet is expanded past design limits. Then, a curious thing happens, and it happens well over the speeds any given bullet was made for: The expansion petals shear off, and penetration increases again.

To test this, I used three different pistols. The first up was a Springfield Armory XD(m) Compact with a 3.8-inch barrel. The second gun was a Canik TP9 with a four-inch barrel. The last was a custom 1911 in 9mm with a five-inch barrel.

I hoped the velocity differences resulting from the three barrel lengths would show some difference in penetration in gelatin. For this test, I used rifle gelatin blocks instead of handgun blocks because they were what I had on hand. The only difference is that handgun blocks measure 6x6x16 inches while rifle blocks measure 8x8x18. The gelatin formulation is the same, and penetration results are the same.

The XD(m) posted the slowest velocities, as expected, and the least penetration. The TP9 showed a small increase in velocity, but if there was a change in penetration, my tape measure didn't show it. The 1911 showed the difference. The speed boost-75 fps over the TP9, almost 90 fps over the XD(m)--provided extra penetration.

The Z-Max from the XD(m) and the TP9 all stopped right at 16 inches. plus or minus a quarter-inch or less. The bullet fired from the 1911 exited the back of the rifle block but did so without enough energy to enter the backup block I always use to ensure I'm able to capture every bullet I fire.

The Hornady Critical Defense and the FTX bullet has come in for some criticism for a lack of penetration in gelatin. Hmmm. The Compact XD(m) and the TP9 both exceeded the FBI minimum, and the 1911 ran right to the maximum, and that doesn't sound like a lack of penetration to me.

The test does show us that some variables matter. If you go compact for ease of carry, you are giving up some (not a lot of) performance in gel and, by extrapolation, attackers.

But there's one more interesting aspect of the new bullets we have at our disposal: consistency. Back in the cup-and-core days, bullets performed differently (for the most part) in gelatin and in water. That was the big reason for using gelatin. Some bullets that performed well in water--producing beautiful, perfect mushrooms--performed miserably in gelatin. They shredded, broke and generally failed. On the flip side, some bullets that came apart in water produced better-than-average results in gelatin. There was no way of knowing, short of trying.

Modern, bonded handgun bullets perform the same, pretty much regardless of whether the impact medium is water or gel. In fact, they don't show much difference in performance until you start putting barriers in the way.

Home Testing

So if you want to get a good idea of the expansion your bullet produces out of your handgun, you can use one-gallon jugs filled with water. You won't be able to get any clear measure of penetration, as the jugs don't work that way, but if you stack enough of them together to capture the bullets, you'll find that expansion on modern bullets will be consistent.

So what have we learned from all this? The most important thing is that you must test your ammo, in your handgun, to get a clear understanding of what is going on. If that means you have to shoot up more than just a couple of boxes to be sure of your sights being zeroed and that your pistol and selected ammunition play well together, well, that's what you have to do.

Second, if your gun club allows it and you're willing to spend some time risking a deluge, you can get a good idea of what your pistol and your selected ammunition will do as far as expansion is concerned. You do have to exercise some care, or else you'll only learn that bullets expand excessively when they plow into dirt.

And, finally, take a moment to acknowledge the efforts of the handgun bullet makers and ammo loaders. They have, in the last couple of decades, completely reinvented the handgun bullet. Those little copper-colored kinetic energy devices might look just like the ones in the faded box on your shelf, the one dating from before the Windows operating system, but they aren't. The only things they have in common are that they are made of lead and copper alloy.

PERFORMANCE RESULTS | HORNADY Z-MAX 115-MAIN 9MM

Pistol          Barrel    Muzzle    Standard      Gelatin

                Length  Velocity   Deviation  Penetration
                 (in.)     (fps)                    (in.)

Springfield        3.8     1,063           8           16
XD(m) Compact

Canik TP9          4.0     1,075           5           16

1911               5.0     1,139          12           18

Notes: Velocities are averages of 10 shots measured on a
PACT MKIV chronograph set 05 feet from the muzzle.
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Author:Sweeney, Patrick
Publication:Handguns
Geographic Code:1USA
Date:Feb 1, 2014
Words:1508
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