10-27-2021, 12:52 PM
The main consideration is the barrel to upper interface. If your upper is billet then it "should" be machined true. However, on many forged uppers, the end of the threaded ring where the barrel is secured will not be truely perpendicular to the axis of the barrel, that is to say that the barrel, when fully seated either will not be perfectly straight with the centerline of the receiver or may be riding on a high spot such that it rocks very slightly - I've seen both. There is a tool that drops into the snout and, when used with valve grinding compound trues that surface. I only use forged receivers and have assembled or helped others to assemble more than 50 MSR's and the only manufacturer that I have encountered where they start off true is Bravo Company. There was an excellent article by Peyton Sweeny in Guns and AMmo Mag a few years ago about this process and the tremendous accuracy improvement this truing process made to his MSRs - highly suggested reading for anyone building their own.
The first Grendel that I built some years ago seemed ideal, but... When I went to the range with it, as the distance to the target increased the POI shifted to the left. After a lot of frustrating discussions with the guys around me, it was discovered that the barrel was actually slightly canted to the side. The "snout" was not faced off properly.
The first Grendel that I built some years ago seemed ideal, but... When I went to the range with it, as the distance to the target increased the POI shifted to the left. After a lot of frustrating discussions with the guys around me, it was discovered that the barrel was actually slightly canted to the side. The "snout" was not faced off properly.