I have been a very big fan of the SIRT pistol, and run it daily. I was given the SIRT AR bolt as a Christmas gift. Unfortunately, it was not a good product at all. The fit was a problem with a stock Colt 6920 (as many other will also attest.) Even once installed, it was clear the laser device itself simply did not work as sent from the factory. The company's customer service leaves much to be desired - essentially, their response was an email blaming user error after quite some delay. It wasn't worth the hassle to argue with them. I cannot recommend at all.