Testing .45 ACP From a Short-Barrel Gun

The first sub-compact .45 ACP- the Detonics Mk.1 Combat Master .45

The question came up this morning about hollow-point bullets from a short-barrel .45. The concern was that the reduced velocity from shortening the barrel would prevent the bullet from expanding. This sounds like a reasonable concern, and something that ought to be tested. Having some Speer 200gr JHPs (the famed ‘Flying Ashtray variety) and a slightly over-used block of Clear Ballistics I decided to find out. For the test I used my Detonics Mk.1 Combat Master .45. With it’s 3-1/4″ barrel it’s ideal for this test.

The load I used was 6.5gr. Unique with a Federal Large Pistol primer, which yields 920 fps. and 376 ft./lbs with an extreme spread of 45fps. from a 5? barrel.

The venerable Speer 200gr. JHP. It’s been around for decades… and it still works!

I draped four layers of denim over the end of the block and I fired across the chronograph and into the block. The bullet clocked 848fps., making 319ft./lbs.Penetration was 14″ (with 1″ of bounce-back in the gel.)

It’s a bit hard to see the wound-track; this block has been used rather a lot!

Expansion was large but asymmetric, measuring .665 at the widest and .615 at the narrowest, yielding an average diameter of .640″. Nothing to sneeze at here!

Weight retention was good as well, losing only a small sliver of the jacket. I’d have no issue whatsoever with relying on this for self-defense.

This bullet was designed decades ago, when the conventional wisdom said that hollow-points would simply not expand at the velocities achieved by .45 ACP. Speer proved them wrong, and today there are several excellent hollow-points available… but the Speer ‘Ballistic Soup-Can’ soldiers on.

Michael Tinker Pearce, 16 December 2020

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