Oooh, look at you getting all fancy and technical! :o @Blaz, pay no attention to MrRaley. He just 'copy and pastes' stuff he reads on FPSRussia and NutnFancy blogs. <lmao> You can also check the individual barrel makers as well. It all depends on how much you were looking to spend (please don't say you were hoping to stay under $200!). $275-$375 will buy you most of the normal barrels. Custom barrels usually run from $500 to $1,000 (mine was $950), but they generally come with a matched bolt. Krieger Barrels, Satern Barrels, Mike Rock Barrels, YM Barrels, White Oak Armament Barrels, Noveske barrels... just to name a few makers. Also check out companies like Si-Defense, LOKI Weapons Syst., LMT and LaRue.