I've been trying to find the perfect SD ammo for my 5.56 M&P15. The likely hood of using my AR for SD is pretty low. It's nice to have stashed anyway. For plinking and shooting paper, I just pick up whatever, brass cased 55gr, JHP, FMJ, whatever is available. I haven't noticed any accuracy issues to 100 yards. Usually Winchester 5.56 rounds or Remington UMC .223 rounds.
I have a 16" 1:9 twist barrel. I've read all over the internet 69gr is typically the maximum for 16" 1:9 barrels as far as accuracy goes. But to what range? I typically only shoot my AR to 100 yards. I've been doing some reading saying that the 75gr TAP rounds are actually pretty accurate in a 1:9 twist 16" barrel to 150 yards.
Also "my opinion" of accuracy may be different to others. I'm not a competitive shooter. 4-5" groups at 100 yards are enough to make me happy. I would think that would be fairly effective in the EXTREMELY unlikely chance I'm defending myself from that distance. Now, how would the 75gr TAP rounds do at 25-50 yards? I'm more concerned about that range. If I have to defend myself from over 100-150 yards, I'm either a dead man to begin with, or I'll use a .308 from a bolt-action.
So, with that said, think 75gr TAP will suite my needs? Will they tumble and fragment at 25-50 yards? And can I find 75gr in 5.56 or just .223?
Figured I'd reply here instead of starting a thread. It's still on topic
EDIT: After a few hours on google, I started to do some research, finding alot of 5.56 bashers. I then came across this:
Next time you look at an M-4 or an AR-15, notice it says “5.56 NATO 1:7” on the barrel. This literally translates into; “the bullet will make 1 full rotation for every 7 inches of this barrel.” This was not always the standard twist set for the new NATO round. The first AR-15 made by Armalite, had a 1:14 twist making it a very, very unstable round. One can only imagine the orientation of the entry and exit wounds...
http://www.futurefirepower.com/myths-about-the-nato-556-cartridge Not sure about how reliable the source is.
So I figure, close range ammo, 150 yards or less, a nice unstable bullet should prove to be more effective. 77 grain in a 1:9 should serve well
As accurate, no, but like I said, I figure 4-5" groups would make for effective placement, in my opinion. and the groups would only be tighter, the closer the target is. And plus, one shot of 5.56 may not prove to be immediately incapacitating, but who pulls the trigger once? They're semi-auto (and select fire for military) for a reason
My brother in-law has served in Iraq twice, and he's very happy with the M4 platform and 5.56 round.
Besides, plenty of people survive 7.62 wounds just like enemy's survive 5.56 wounds. The old shot placement quote is not a joke.
I've often thought of buying a 6.8mm upper. I'd rarely target shoot with 6.8mm, maybe to dial it in, but would it really be worth having an entire upper JUST for SD or HD use? I've thought it over, an no, it's just not worth it to me. 5.56 should suit me well.
Sigh, anyway, these are just my opinions. Take it for what it's worth...