Does Short Barrel = More Penetration Due to Lower Expansion?

[Aristides]

Let's assume a specific bullet, such as the Golden Saber 230 grain 45 ACP (or any quality ammo).

Now let's assume I have two pistols: a Colt 45 Commander with a 4.25" barrel, and a Colt 45 New Agent with a 3" barrel.

I've assumed that I should carry my Commander whenever possible, because it will be more effective if I need it. That is, longer barrel = more velocity and more power, and therefore more penetration and terminal effectiveness.

But, I've been thinking...higher velocity usually results in more expansion, which actually REDUCES penetration. So, will my 3" New Agent provide more penetration than my 4.25", all other things being equal?

[Jim Watson]

I understand your theory but it would be a fine line between expansion and penetration.

I don't guess you could shoot the guns into some sort of expansion medium and find out for sure.

[s4s4u]

The differences invelocity are not sufficient as to warrant such scrutiny.

[Aristides]

I don't have any test medium. I've browsed around the internet trying to find a comparison test that addresses this, but haven't come across any.

It seems to me a worthwhile question. Everyone seems to emphasize longer barrels, and there seems to be an attitude that short barrels are a compromise for concealment's sake. But if short barrel means more penetration, and assuming you already have plenty of expansion as would be the case with 45 ACP, well then...I'll carry my New Agent a little more than I currently do!

Yes, someone will point out that my Commander has one extra round, and a little longer sight radius to aid in accuracy. But I'm very accurate with both pistols, can't really tell any difference (I'm surprised and pleased at how accurately I can shoot the New Agent). So, really, the trade-off is that one round. I don't casually give that up. But given that the New Agent is more concealable and more comfortable for all-day carry, if it really is likely to penetrate as well or better than the Commander, that would change how I think about my New Agent (and my XDs, too!).

Hopefully others can chime in.

[Chuck Dye]

As I understand it, penetration is a function of momentum and cross sectional density. In an expanding bullet, cross sectional density varies as the bullet expands, expansion varies with velocity and the resistance of the target. With a rigorous program of testing in multiple media and multiple impact velocities, you might draw some worthwhile conclusions after great effort and expense. You would be far better off investing the time, effort, and resources in training and practice. Useful shot placement in a timely fashion can trump terminal ballistics. To borrow from an old friend comparing the .30-06 and the .30-40 Krag "Hit'em right, and the deer don't seem to notice the difference," I doubt the bad guys will, either.

[James K]

Penetration vs expansion has more to do with bullet construction than with velocity, barrel length, time of day, or any other factor. And none of those things really has a lot to do with lethality, where the location of the hit is the overriding factor.

Expanding bullets are often touted, especially for police, not because they always cause greater tissue damage but because they reduce or eliminate over-penetration. Some states ban use of expanding bullets for SD because of the supposed cruelty of expanding bullets, but in doing so, they end up requiring the use of full jacket bullets and increase the probability of wounding or killing innocent people who happen to be behind the initial victim.

Jim

[Aristides]

I agree that location is the key, and after that, penetration. For a self defense situation, I believe the bad guy needs to be stopped immediately, which means deep penetration to the vitals, preferably CNS.

When I carry my more compact and shorter guns, I have assumed I'm sacrificing power and thus penetration. Now I'm wondering if the opposite could be true.

The responses are appreciated and have been helpful, but they can be summed up as "it doesn't matter". Well, we can say that about alot of the discussions on these forums. "Just hit 'em center of mass, and they'll go down." It doesn't matter whether the hit is with 9mm, 40, or 45. That may be true, but we still like to discuss and debate the details.

So, I'm still wondering whether the shorter barrel does, in fact, give better penetration. Does anybody know?

[JohnKSa]

When I carry my more compact and shorter guns, I have assumed I'm sacrificing power and thus penetration. Now I'm wondering if the opposite could be true.

My gut feel is that it's going to be pretty much a wash. You'll get a little less expansion which means that the lower power will be able to push the bullet about as far (given less resistance from the reduced expansion) but not much more than that.

There's no way to know for sure without doing a lot of testing.

The bottom line is that we have expanding ammunition for very good reasons. Even if you do get a little more penetration because the bullet didn't expand well, that's still not a good thing because you really wanted (and paid for) that expansion. It might be reasonable to say that it's just not quite as much of a bad thing as it could have been.

[big al hunter]

Wet paper makes a decent media for testing penetration between cartridges or velocities. You probably need 2 feet of wet newspaper to stop 45 auto. Fill a couple of cardboard boxes with paper and soak it. Then shoot a few shots into it. Empty the boxes slowly, in layers until you find the bullets an measure. Then let us know your results.

[tipoc]

So, I'm still wondering whether the shorter barrel does, in fact, give better penetration. Does anybody know?

In addition to the wet pack (or any other medium that you care to use). A velocity gauge would be helpful. If you're going to look at it seriously anyways.

It seems that you're assuming that the bullet will be slower from the 3" barrel of the New Agent than from the 4 1/4" Commander. This may not be the case. The small differences in internal dimensions of a barrel and gun can make differences in how a given manufacturers bullets behave, including how fast they leave the barrel.

The difference in velocity may also be so slight between the two that it makes no practical difference in potential for the bullet to expand. If 40 fps separate the two that really won't make much real world difference that you could count on.

In other words you'd need to test specific ammo out of a specific gun to see what velocities you're actually getting. It will vary from brand to brand and bullet type to bullet type.

There is a good article on just this topic in the Aug. 2013 issue of "Handloader" magazine.

You can do the testing and in the end you'll know a bit more about your guns and some ammo for them. You'll also know how they perform in specific test media. This can help some. You'll likely not have to defend yourself against test media, but it does help to know what you can maybe expect.

Course the jhp could be damaged on the way in, or be plugged and so act like ball anyway, but this may show up also in any tests.

tipoc

[Paul B.]

I'm thinking the difference in velocity would be negligible in a self defense shooting. If the normally considered thought of most SD shootings are at 21 feet or less, just how much difference would possibly a 25 or 50 FPS difference in speed make? Anyway, you're probably gonna double tap anyway or possibly even dump the whole magazine into the BG due to adrenaline rush ( fight or flight) so where's the problem?
Paul B.

[MK11]

No, the shorter barrel does not offer more penetration. And if the difference between adequate penetration and insufficient penetration is one inch of barrel, you need to change your ammo.

[jmr40]

I'm thinking the difference in velocity would be negligible in a self defense shooting. If the normally considered thought of most SD shootings are at 21 feet or less, just how much difference would possibly a 25 or 50 FPS difference in speed make?

It depends on the gun, ammo, and exactly how much barrel length you are talking about. Comparing a Glock 19 to a Glock 17 with a 1/2" barrel length difference you are right on. But comparing a 357 revolver with a 6" barrel vs one with a 2" barrel could be 500 fps or more difference.

In the case of magnum revolver loads barrel length would have an impact on the ammo I chose. With most semi auto's not much at all.

[Tactical Jackalope]

It would be such a minuscule difference if any at all to even worry about.

[mavracer]

Since there are vairables between barrels that affect velocity, theres no guarentee that your commander will have any velocity advantage over your agent.
And while less velocity could equal less expansion which may increase penatration, it also equals less momentum which will may decrease penatration.

[Webleymkv]

JHP bullets are typically designed to work within a certain window of velocity. Usually, the bullet is designed to expand and penetrate optimally at a certain velocity and still perform acceptably within a window of at least 100 fps above or below that velocity. Also, most cartridge have a given barrel length that is considered to be "standard". Since you brought up .45 ACP, the standard barrel length for that cartridge is 5" because, for many years, that was the most commonly encountered barrel length for a so-chambered pistol.

Now, the 230gr Remington Golden Saber you mentioned (I'm assuming the standard pressure version rather than the +P) is advertised at 875fps from a 5" barrel. I would expect optimum expansion and penetration to be achived at or around 875fps but I'd also expect acceptable expansion and penetration at velocities anywhere from 750fps to 1000fps give or take a few fps. Since most 3-3 1/2" barrel .45's can still spit a good 230gr JHP loading in the high 700fps to low 800fps range, I would expect your Golden Sabers to still give you adequate, though probably not optimum, performance from the 3" barrel of your New Agent.

As far as whether or not they'll penetrate more, they probably will but at the cost of less expansion. Since Remington designed the bullet to expand and penetrate optimally at higher velocity, it seems to me that you're robbing Peter to pay Paul by reducing expansion to increase penetration. If more penetration is what you're after, I think you'd be better off simply switching to a different bullet construction that offers more penetration at optimum velocity.

[rc]

Depends on so many factors that may include the type of projectile. If a bullet starts to fragment, the penetration is reduced for a particular caliber and bullet weight. A 230FMJ will penetrate more than 230JHP assuming the JHP opens up.

[PatientWolf]

Either will get the job done.

[ckpj99]

In SD situations, most people do NOT want maximum penetration. You however seem to want the opposite, which is a separate argument. If you really want maximum penetration, then shoot full metal jacket ammo or, hell, even solids. This is why the question is being brushed off.

To actually answer your question, in your situation, the shorter barrel WILL NOT result in deeper penetration. Golden Sabers are an easily expanding bullet. The bullet will expand as designed as the muzzle velocities produced by either barrel length.

The extremely small difference in expansion is NOT enough to make up for the velocity difference in the barrels.

In other words, let's say that your Golden Saber ammunition travels at 900 ft/sec out of your longer barrel (which is close to accurate). Out of your shorter barrel, you'll loose velocity, probably 75-100 ft/sec. The Golden Saber will expand almost exactly the same way, maybe only a few hundredths of an inch different. The expansion of that type of bullet is almost binary (it either expands or doesn't, there's little in-between). Therefore, the velocity difference will lower the penetration more than the lack of expansion would increase it.

All that being said, the difference would be negligible. I would guess 2-3 inches in deep ballistic gel at the most.

In different calibers with different bullets, this may not be the case. In fact, with Golden Sabers (which have been known to clog when doing a 4 layers of denim tests in some loadings) the clothing of the target will probably play a much bigger role than the barrel length.

[s4s4u]

I've been thinking...higher velocity usually results in more expansion, which actually REDUCES penetration. So, will my 3" New Agent provide more penetration than my 4.25", all other things being equal?

But less velocity equates to less momentum and even if there were less expansion, the loss of momentum would negate any potential significant increase in penetration. If you want more penetration, shoot hard cast or FMJ's. A 1/2" diameter slug needs no expansion to do the deed.