Took the brand spanker new Model 1 upper to the range....Feeds supersonics like a dream..wouldn't feed sub for didly...I ended up clamping a chunk of innertube over the muzzle with a hose clamp.... subsonics fed very reliably untill the rubber got too blasted away ( usually about 5-6 shots) Sooooo... Tomorrow we get a chunk of 7075 and spin up a Noveske-esque, brake/ flash hider to try and give this turkey enough back pressure to feed subsonic loads without issue, the things you do to save a few scheckles.... Of course I could go for some heavier blast resistant rubber
