When I started my "AR10" build,,,I didn't know about different mfg parts not fitting together. So, I had bought a DPS bbl in 260 rem, because I knew 260 bbls were hard to find. Then asked my wife ( who got me into this whole thing,LOL!!) to order the "other" parts to put it together. She orderede the RR because she thought them well made ( after 30 years of being married to me, a gunsmith) she knows quality from poop. Got the local gunshop to order the parts, told the wife I wanted to be surprised, and didn't want to know what she ordered, and just waited. Don't really know how long I waited, but the shop called, and said my parts were in, it was like Christmas!!!!!! Been very happy ever since! Everything has been well worth the wait! Respectfully Terry