VKTR Industries AR-15/AR-10 Gas Key

The gas key sits on top of the bolt carrier and catches the gas tube. Every cycle of the action runs through it, so a key that leaks or works loose turns into a rifle that short strokes and stops feeding. This one is steel with a nitride finish and fits both AR-15 and AR-10 carriers.

Plan on staking it once it is torqued down. Staking is what keeps a key from backing off under repeated gas pressure, and it is standard practice on any carrier put together from parts.