This is a visitor’s AR-15 built using an Olympic Arms 16 in barrel. Tobe, the owner, tells me that he has never modified the barrel as it came from Olympic Arms. Tobe says he uses the standard carbine gas tube as opposed to the adjustable gas systems that seem to be commonly required. With his upper, Tobe tells me that he gets perfect operation with both a supersonic and subsonic load built up around the 190-gr Sierra HPBT.
The subsonic load Tobe uses involves a 190-gr Sierra HPBT match bullet, 11.0-grains of Accurate Arms 2015 powder ignited by small pistol magnum primer. The supersonic load he uses is a 190 Sierra HPBT match bullet on top of 17.0- grains of Accurate Arms 2015 powder ignited by small pistol magnum primers. Tobe said that the supersonic load produces 1495 to 1510fps from his upper.