Last week we took a look at how M855 5.56mm ball ammunition stacks up in terms of accuracy, and this week we are looking at its terminal performance. We are using ballistic soap, which retains temporary cavity structure, and thus make for a more readable result than the more common ordnance gelatin. This particular soap has rather more resistance to penetration than human tissue, and penetration into it is increased by a factor of 1.5 to simulate humans.
We compare the M855 to NATO 124 grain 9mm ball ammunition fired from a pistol, and also to M193 Lake City 55gr ball, Mk262 Mod 1 77gr open-tip match made by Black Hills on government contract, and Wolf 55gr ball. The results of the test show that for terminal effectiveness, any of the other 5.56mm options are better than the M855 - even the cheap steel-cased Wolf.
All testing was done at a range of 15 feet, and the same rifle was used for all the 5.56mm testing. It had a 14.5 inch barrel with a 1:7 twist rate, duplicating the technical specs of a military M4 carbine.