A re-post
The .40 v .45 FMJ issue…
I have opined in print that there isn’t enough difference between these rounds, to matter. Another thing that brought me around to the .40 was a couple of informal bullet tests I did a couple of years later- using bargain ammo:
06/09/05-
Keep in mind that this is not a scientific test, and it does not relate performance on water jugs to performance on humans. What it does do is relate the performance of typical .40 FMJ to .45 FMJ ammo and guns, in the same medium. I shot what I had on hand. In .45 ACP, that was Wolf 230 hardball. You can look the ballistics up if you want, but it is consistent with other round of that caliber and type; 850 fps or so. In .40, I used Remington UMC 180 FMJ, which is a flat-point bullet at a listed 985 fps.
Test guns were a 5" Springfield MilSpec and a 4" Springfield XD-40. The unfired rounds and recovered bullets appear below:
I find it interesting that the .40 actually riveted a bit, and the jug shot with the .40 jumped a bit, and showed some swelling on the bottom (impact) end. I managed to precisely center that jug, so the bullet shattered the cap on the way out. The jug shot with the .45 ball barely moved. The jug hit with the .40 also ruptured, and the jug shot with the .45 did not. Take this for what it is worth.
Both bullets penetrated to within 1/4 inch of the same depth, with the edge going to the .45 here. Neither of them penetrated the catalog, which was dry and about 1.5 inches thick.
What did we prove here? Does the .40 kick the old .45's hiney?
No, it does not; but it offers a similar, if not better in some cases, performance to the old Colt round, in a smaller package. I would not be at all bashful about carrying .40 FMJ flat-point in a military or defensive handgun.