I had a local gunsmith build an AR15 upper for me in 300/221, and a matching barrel on a Savage bolt action. Specs on the AR barrel - 16.5", 1:8 twist McGowan barrel, TP555 3 position gas block in the pistol position. The lower is equipped with a commercial 6 position stock, and DPMS GI trigger. I want to change both of them eventually and get a better trigger and a stock thats better for shooting off the bench, possibly just an A1 stock.
I had it threaded for 5/8 threads, and supplied a YHM suppressor mount to install on it. My intension is to buy a YHM 7.62 suppressor and share it between the 2 rifles- -the mount that comes with the YHM Suppressor will go on the Savage.
As it happens friend of mine has a YHM 7.62 suppressor, and came down to shoot it with the 300/221.
I'm still smiling.....suppressers and subsonics are awesome! A suppressor is now on my VERY SHORT LIST of things to buy! (...and a 300/221 is on my friends short list now)
My issue - It cycles fine on supersonic stuff in the middle gas position, but when shooting subsonic loads in the full open position, it was short stroking. Very close to functioning properly though, as it ejects with athority, and resets the trigger, but the bolt is just not coming back enough to strip the next round off the magazine. The bolt fully closes, and you just get a click when you pull the trigger on the second shot.
I'm using VN110, under a 240gr SMK, Fed 205 primer. With 9.0 and 9.3 grains of powder they were coming out subsonic, at 9.7 grains they were supersonic. According to the Sierra loading data, 9.7 should be 1050FPS, 9.3 should be 1000fps, 9.0 around 960fps.
Would a different powder help? If so, which should I try next? I'm assuming I would want a faster powder? Would a lighter buffer help? Which one? Can you cut the buffer spring down?
Short Stroking in Subsonic AR15
Threaded Mode