MSTN offers full custom AR' rifles, pistols, and SBR's (all N.F.A. regs apply) in 5.56, .300 Blackout, .308 Winchester, and 6.5 Creedmoor calibers. The "small block" guns are available built on receivers by: 2A Armament, Vltor, V Seven, SanTan Tactical, or Seekins. The "big block" guns are built on JP Machine billet receivers. Barrels are available from both Noveske and Bartlein.