We developed these little rails for a customer that wanted his red dot to be spot on every single time. Since they are mounted to the top of the barrel, and not the receiver, they stay true to the bore axis regardless of the minute differences in barrel / receiver alignment when removing and re-installing the barrel. Each rail comes with (4) 6-48 mounting screws.

NOTE :These require PROFESSIONAL gunsmith or qualified machinist installation. This is not a job for a hand drill. Designed and warranted for mounting on a STEEL barrel only.

Found here :

https://dlaskarms.com/products/ruger...picatinny-rail