Doc Torr wrote:1. Overpenetration is BS. USe better quality ammo, the surplus stuff is for practice.
2. Use better quality ammo. Compare Mk262 77gr OTM (designed to be magic-killer-super-awesome out of a 10.5-14.5" barrel, but still awesome out of a 20") to M855 ball. Mk262 wins every time. Same goes for surplus x39 ammo vs the Hornady SST loadings.
3. Didn't we already have a discussion about the mostly-myth of overpenetration?
Against a hard target (wearing armor) overpenetration would not occur with a 5.56 round out of a standard M16 rifle length 20" barrel. Definitly would not occur with anything shorter. Unarmored? It's possible (doubtful), maybe depending upon how husky the target is. Chart is showing penetration 30cm to 65cm. You have to think about exactly how much lenght is there from your belly button to your spine (35cm to 45cm maybe?)
Well, if you use ammo designed to penetrate armor, you might have a slight issue, although there are some other things to consider: 5.56 and 5.45x39 are designed to yaw wildly with he 55gr and 62gr M855 rounds. It won't be a straight clean shot through and through. Other things missing are the media, method of testing, and the barrel length of the weapon firing it. Ballistic gellatin is great to test penetration, but it doesn't tell you squat really about how the round will behave in actual flesh, blood and bone, other than giving you a visual aid of "this is how it would fragment and travel in a 100% homogenous substance that sort-kinda acts like flesh.
But back to round choice: Don't use M855 for defense unless you think you're gonna go head to head with people a lot better equipped and trained than you. Off the top of my head, there are seven different loads I would choose first: 77gr Sierra BTHP, 77gr Nosler BTHP, Hornady 75gansta, Mk318 OTM, 55rg XM193, Hornady SST 62gr, Hornady 69gr are all better choices, assuming you match the load to your barrel length and spin. 1:7 should stabilize all of the above well enough for anything under 300yd, although I haven't tested it myself.
For the Rusky ammo, everything but the commercial JSP was FMJ, which leads me back to my initial advice: use better ammo. Use ammo designed to be used for heart and lung shots to drop the target as quickly as possible, and then practice (get training) so you can put them there.
Lastly, there's the matter of energy remaining: how much energy does the round have after it leaves the target? Call of Duty=/=the real world, you can't drop 2 guys standing ten feet apart with a single 7.62x39 delivered COM just by lining them up, especially if you get ammo designed to be used against unarmored targets.
If you really think you're gonna face off against guys with plate carriers, move. You won't win that battle more than once or twice.