[at4rxj]

So on the AR I just built with the heavy fluted varmint barrel, it's obvious to me that I can't use a standard gas block. I was considering getting a quad rail gas block, but don't know if I need to order a specific diameter or get one of the ones that clamps on???

thanks in advance

[BattleRifleG3]

Very good question. The barrel diameter are usually one of several standard sizes. There is a different gas block for each barrel diameter. It should be listed in the data for the barrel and in the data for the gas block. If not, I would call the manufacturer or distributor of each. Whoever sold you the kit should know.