I just bought a 24" 8tw Criterion Bull barrel for a new upper build using a DPMS Low Pro upper receiver. 80 grain Nosler CC loaded to 2.505" COL are just short of the lands with 2.513" being jam. Using Varget and BR-4's produced a .404 MOA 5 shot group at 100 yards and I will load more looking for consistency and velocity. I noticed that Fulton Armory offered the same tube in 12tw so I called to see if they had the reamer print hoping there would be less freebore for Mag length loaded lighter bullets. I was first told not to use reloads as it was not safe! I tried to assure him that I kinda knew what I was doing and asked again about the freebore. He told me that I would have to measure it with a Stoney Point. I don't have the barrel to do this and wanted to know before the purchase! He finally said it was the same reamer as the 8tw but the freebore can change due to the barrel extension!
He then said they won't give out that information, which I still don't think he knew what I wanted, and went back to the reloading and said it's not the powder but the headspace I should be worried about. I once again assured him that I measure it with a Larry Willis gage, probably didn't know what that was, and adjust my dies accordingly. I thanked him for his assistance and hung up. Whew, at least the barrel seems to be a "Keeper"!
