HI, We "currently" have three sku's available of the M&P10. A Camo/Realtree hunting model, and two LEO/MIL models. "At this time" due to the limited availability we are only offering the LEO/MIL version to law enforcement and military customers due to the demand.
THe Barrel is a 4140 Chome Moly barrel, (Durable Corrosions Resistant Coated- a Nitride type coating) that has proven to be extremely durable and long lasting, as well as accurate. The barrel features 5R rifling and 1/10 twist and is chambered in .308.
TheM&P10 is compatible with Magpul/SR25 style magazines, and can accept other aftermarket magazines that are based on the SR25 Specs.