1stSFOD-Delta wrote:
Dad's building a 12" Stealth with a Noveske barrel in 300 Blackout.
Don't know if we're going with a AAC 762SD or a Surefire FA762K.
If it's a coin toss, why not throw the AAC on the 300
AAC?
Only real "gotcha" I've heard with the 300 AAC is that the subsonic loads require a 1:7.5 twist or faster.
Otherwise the accuracy goes to "minute of barn door"
(AAC approved subsonic load: 11.2gr AA1680, 220gr Sierra MK, case 1.368", overall length 2.089)
And, with a 12", you might want to look at a piston system.
12" barrel + suppressor + direct gas =
VERY dirty gas system,
whole rifle gets hot quickly,
short-stroke & general oversensitive timing issues from a carbine gas system,
and too much of that dirty hot gas comes spilling out past the charging handle into your face.
If you do go for a direct gas system, I
think the gas ports are 0.075" for the 110-125gr supersonic rounds, and 0.100" for the subsonic 220gr
For a 20"+ barrel DMR on semi-auto, direct impingement gas system is more accurate than a piston, and the cleaning schedule isn't too horrible.
For a short barreled, suppressed, auto(?) rifle, the piston system is a perfect compliment.
I'll probably go with the 16.5"-18" barrel mid-length in 300 AAC myself.
Last edited by rdx-fx (2012-05-26 08:37:54)