After reading some recent threads on ballistics on 5.56 SBR, I find myself searching for answers to a problem that may or may not exist.



I have a 10.5in SBR chambered in 5.56 and a midlength 16in chambered in 6.8.



Am I to believe that what I heard, that the 5.56 out of a 10.5in upper will not fragment past 50 yards and renders the 5.56 an ice pick?



Honestly, should the 5.56 be bear minimum of 16 in?

The best load I've found for the 10.5" 5.56 is typically somewhere around 40-45 yards. That's with the Hornady TAP 5.56 75gr BTHP/WC T2. But that being said, I don't see anything wrong with that for what a 10.5" rifle is normally used for, i.e. room clearing, etc. Just know your weapons limitations and pick the right weapon for the mission. I have both 10.5" and 12.5" 5.56 rifles and use them for what there abilities are.

Thanks for the info. I'm going to be honest and tell you that I got the 10.5 in 5.56 because it looks cool and make the task i.e. logistics of lugging a suppressor around easier.

Yeah, it's a beautiful length and wonderfully effective for Home Defense since you can mount a suppressor and still be fairly short.

The 6.8 is really the best thing going in the AR-15 platform. I'm considering pulling the 5.56 upper and just leaving it in the safe and building a 2nd 6.8 upper as an SBR.



The 6.8 is the perfect balance in all things ballistic in the AR 15 platform given the overall weapon weight I find most appealing.





Would you care to post a pic or two of the 12 inch 6.8 you speak of?



 

I stand corrected. Interesting since I'd found a number of threads that mentioned the T2 was the hot setup out of the 10.5" barrel.

No personaly 6.8 experience here, but from what I've read here and elsewhere, 6.8 is hands down, the better cartridge out of a SBR.
That said, keep in mind that most complaints about terminal effectiveness of 5.56 relates to military grade FMJ ammo. Us civilians are not bound by the same ROE. We can use non FMJ ammo. TAP is good, but there are others out there. You can turn a 10.5" 5.56 SBR into a mean sucker with the right ammo. Go heavy, go as fast as you can and go HP or SP. I suspect that a good varmint bullet on top of a good case and powder should do it. If you have the cash, go for a 6.8, or better yet, 458 :D Ultimate HD cartridge - even if you miss the BG, he'll still pass out!

My 10.5" 6.8 Noveske fires the 85gr SSA Barnes tactical loads at 2830~ish FPS.  That will clear a room and kill a deer/hog at 200 yards...

I have some heavier loads I'll be testing as well (110gr Prohunter), and a sub load using the Hawk 130gr bullets...

Looks kind of like mine

http://i890.photobucket.com/albums/ac110/RFuhr/093.jpg