If you want to ensure rock solid reliability on your rifle, pinning the gas block to the barrel will ensure that it remains in place regardless of your firing cycle. At this time we only pin solid (set screw attachment) gas blocks.

If you are looking to have an A1 or A2 FSB pinned to your barrel, please use this service instead: https://www.rainierarms.com/pin-a2-front-sight-service-only/