Any Experience with AR Shorty .300 Whispers?

[Scoop]

I've got a registered SBR lower that presently doesn't have an upper on it so I contemplating a new build. I have a 16 inch Olympic 1x8 twist .300 Fireball barrel with the pistol-length gas system. Looking at building a dedicated Subsonic launcher for my 220 gr SMK loads in an "SD" type format. DD or LaRue rifle length rail, take the barrel down to 10.5 inches and use my 9mm pistol can for a short, light setup. By my calcs I'd have about 5 or 6 inches of can sticking out from under the rail. Should look really good. Add a Leupy MR/T for optics and viola!

My question is this. Will a 10 inch barrel (again, pistol-length gas system) still be reliable with subsonic loads? Anyone have any experience with short .300 Whispers?

[tp555]

When you get to 9" or 9 1/2" it gets hairy.Variables are: barrel mfg,some blanks
are tighter then others, powder If you reload. Slower burning powder increases
the recoil pulse time and size of gas port.A 1/8" dia. port hole is about max.I
have drilled gas ports up to .156" in other calibers. The disadvantage is the larger the gas port hole the more chance of scraping a bit of copper jacket that gets into the gas block and clogs up.regards.

[ranger dave]

where to start i have a sbr in 300 whisper i started with a 10 inch tube and went to a 12 inch the 2 inches made all the difference in the world i would not go under 12 with a pistol gas tube if you can get a pig tail gas tube all the better now on to ammo you can get sub sonic loads out of a 12 inch tube useing 147g fmj with 8g of 2400 i worked for socom in the early 90 s the 220 - 240 bullets were chosen for pure knock down on bad guys so save some money and shot a cheaper bullet also never ever use the loads from ssk in a shortey with a pistol gas tube there are to hot remember ssk has a gas reg system i have a full size a2 with a full size gas tube for supper sonic the 125g bt is a ground hogs worst day dream feel free to email me for more help shoot_ranger@yahoo