My 10.5 300blk (odin works barrel, stag arms upper and bcg, standard buffer) ran fmj subs and supers just fine, but it had trouble cycling subsonic hollow points (all brass cased ammo). Changing to magpul gen 3 300blk specific pmags solved my cycling issues. Changing mags may not solve your problem, but it might be worth a shot before you do something big like drill out your gas port.