you could have done it without sounding bitchy lol. I made an assumption...JTs measurements seem to confirm that assumption. If the assumption was wrong and you have thoroughly tested thousands of 308 16" rifle gas barrels than great, we can move on to other areas of troubleshooting. That's kinda what we do here btw. Get 308ARs running. We don't have hundreds of members per week shooting 900 yds, but we do ok anyway. We may not have a huge active membership, but tons of people do pass through here on the quest for info. Keep that in mind.