I bought a precision AR in .308 a few weeks ago and have put about 300 rnds through it over the past few weekends. The rounds fired were a combination of 150gr Remington UMC FMJ, MagTech .308 150gr FMJ, and my handloads with varying charges of Varget and 178gr AMAX's. Some of the hotter handloads showed some pressure signs such as flattened primers but the powder charges were still a full grain below the listed max charge in my manual. Funny part is the MagTech ammo was very underpowered and caused short stroking, yet still exhibited the same case bulging. Cases from all three showed a bulge at the case head that measures .480" at the widest point, where it should be .473" at the rim. When resizing some cases my RCBS full length die actually scraped brass off of the case wall and formed a ring forward of the rim. Others are extrememly difficult to resize. I though I was not using enough case lube but even after heavy lubing I ran into the same issues.
After having this issue I took some factory new .308 rnds and dropped one into the chamber. The chamber is loose and the MFG has told me this is part of the design to allow the feeding of various types of ammo, but I can almost slide a .010 feeler gauge between the round and the chamber wall. It seems too sloppy to me. I'm going to get a chamber cast done but does anyone else have any suggestions?
CMS
After having this issue I took some factory new .308 rnds and dropped one into the chamber. The chamber is loose and the MFG has told me this is part of the design to allow the feeding of various types of ammo, but I can almost slide a .010 feeler gauge between the round and the chamber wall. It seems too sloppy to me. I'm going to get a chamber cast done but does anyone else have any suggestions?
CMS
