I've got two Atchisson kits made by Ceiner. Both run fine in semi, with just about any ammo (I used Rem. Golden Bullet 36gr HP and Federal copper-plated 36gr HP in the 550rd bulk packs). The Atchisson kits are also made by Spike's and CMMG now, so there are other sources than Ceiner. 10rd mags are standard, steel 30rd and plastic 27rd (black dog machine) mags are also available.

Only one of my kits runs right in full auto, and only about 95% of the time - but that won't be an issue for you unless you've got an M16 lower or RDIAS.