Mine is a home brew DPMS upper/lower Krieger 26" barrel the bolt is the typical DPMS .080" firing pin opening and it causes me issues with pierced primers which is very common with 6.5 Creedmoor AR's my gas system is maybe a 1/4" longer than a standard AR-15 rifle length system barrel bolt and gas tube all came from Fulton Armory I don't believe they will even sell the .080" bolt with AR 6.5 barrels any longer it was so common of issue.