09-18-2015, 01:57 PM
Type 1 (.125 face depth) are typically used in 7.62 X 39 AR-15's. When Colt sold 7.62 X 39 AR-15's they used .136 depth bolt to have better extractor clearance and for added strength. When AA intially started selling 6.5 Grendel's AA adopted the .136 bolt face depth which has since been standardized by SAAMI. Black Hole Weaponry sold 264 LBC barrels and chambered barrels with both bolts and coined the Type 1 which they produced the most. To satisfy customers BHW sold barrels which used .136 bolts which they identify as Type 2. Upon 6.5 Grendel being SAAMI type accepted AA has released the marketing rights to using the 6.5 Grendel name and chamber. If I remember correctly the typical 5.56/223 bolt face is .125 and is why some 7.62 X 39 bolts end up being .125. Both type bolts are compatable with the various 6.5 Grendel ammunition however you have to use the appropriate bolt for how your rifle is chambered, Type 1 or Type 2. You can not use a barrel chambered using a .125 bolt then swith to a .136 bolt or vise versa.