9mm and .45 ammo: Increased velocity and change in penetration?

I acquired the impression from reading things over a period of years at hollow point round will typically mushroom out quicker and penetrate less when the velocity is increased. I was at Lucky Gunner website and read over the tests they did with various calibers and brands of ammo. However, the pistols they typically used had barrels a little on the short side. With a longer barrel there is more velocity.

An example of the above, though not related to the Lucky Gunner tests, is the old-school 9mm Federal brand 115 grain hollow point at standard and +P+ velocities. With the standard velocity one, penetration went through the whole ballistic gel block and didn't expand. OTOH, the same bullet pushed at +P+ velocities penetrated much less and mushroomed out a lot.

Sticking with 9mm and .45, which hollow points are less likely to mushroom out quickly and penetrate more with a longer barrel and higher velocity? OTOH, which hollow points are more likely to mushroom out quickly and penetrate less?

 

Hornady XTP

Federal HST

 

You can get an idea by looking at the Lucky Gunner results for 38 Special and 357 Mag. They ran all the tests for these two using both 2 inch and 4 inch barrels for each cartridge.

 

The wild card is bullet construction. Bullets are designed to expand within a certain impact velocity range. Too fast and they over expand, too slow and they don't expand at all. A bullet manufacturer can design a 124 gr bullet to work best at around 900-1000 fps. Or they can design a 124 gr bullet to perform best at 1200-1300 fps. Shoot either bullet too slow, or too fast and you'll get sub-par performance.

 

The other wild card is shot placement. Hitting bone can really pump the brakes. I dug out a Hornady XTP from a deer that I hit on the move, quartering toward me and uphill. While my shot placement would have been correct for a level shot, it instead drove upward and into the spine rather quickly, leaving a nearly unexpanded bullet minus a few petals.

What jmr40 wrote however refers to bullet design/engineering and is your best guide as to a starting point for selection.

 

I have the impression modern bullets will expand at a wider velocity window than older ones, thus being less likely to under-penetrate at relatively high velocities and more likely to expand at relatively low velocities.

 

Thanks. This is an example of what I was looking for. I'm not surprised to hear that about those Federal HST bullets.

 

I have a hard time believing if I shoot any hollow point out of a Beretta 92, 9mm ... that there is any physics involved that would make the same hollow point somehow less effective shot out of a Ruger PC Carbine going 100 or 200 fps faster.

 

Gold Dots tend to keep expanding with increased velocity. Sometimes flattening out to where the bullet looks like a starfish.

 

HST bullets referenced above will penetrate less if the Ruger Carbine pushes it 200 fps faster. Possibly much less.

 

Less effective in that the energy available will be used expanding the bullet more and crushing a wider channel through flesh. But you'll have more total energy available because of driving the bullet to higher velocity...

You can probably over-drive JHPs by shooting them at too high a velocity such that the bullet fragments instead of staying intact.

BSW

 

Someone call Paul Harrel and see if he can whip up some meat targets ...

 

HST penetrate fine, but they do tend to open better than many competitors. They are a fine round by all accounts.

XTPs definitely are good for penetration, I like them for woods loads in my 10mm for just that reason.

I think there aren’t too many big expansion, poor penetration rounds being made by the big manufacturers anymore because the FBI standards have been around for long enough everyone is tailoring their rounds to meet those requirements. It’s why I think these days any of the quality rounds are pretty much equal, they are designed that way.

The ones I would suspect would be any of the light for caliber high velocity or fragmenting rounds (what was that one with the copper petals that sheared off… RIP?) but even then these days it seems the light for caliber rounds have been tending to be those solid screwdriver rounds, which are interesting but I’d like to see real world results with

 

Thanks for the replies, all.

 

Yes, 124 standard pressure Gold Dots can expand to the point where penetration is much less. Turn down the volume before watching.



I got better results with Hornady Custom ammo with the 124 (edit) XTP, with the jacket getting stuck in the back of the third jug and the lead core going into a 4th when fired out of the carbine. On the other hand, the rounds fired from a Sig P365 and a P365 XL both penetrated into the fourth jug with good expansion and no lead core separation from the jacket. Unfortunately, the video didn't turn out right. You can do your own testing very easily.

 

Which gives a more realistic result in regard to penetration and expansion in a human body, water jugs or denim and ballistic gel?

 

The gel, when correlated with street results. I think that water jugs are better for expansion potential.

 

It’s simply lost the energy to expand. Imagine shooting an carbon arrow into a tree. Thump. It sticks. It is otherwise much the same as when it left the bow. Now imagine the same arrow being shot from some new wonder bow at say a ridiculous 3,500 fps or roughly 10x normal speed. Same tree target, much different result. And in the case of HP bullets, expansion is engineered unlike the carbon arrow that’s now splinters.

 

I like to think of a hollow point bullet as a parachute. At very low air speed the chute opens slowly (if at all) and doesn't fill completely. More air speed opens the chute quicker and more completely. Some bonded bullets like the Gold Dots continue to expand down the base of the bullet and the petals continue to flare out passed what they were designed to do. The result of too much velocity is a stretched out parachute, very large in diameter, that slows down too quickly.