Without telling you to look into something else entirely, as others have suggested, I have to say that my luck with .22lr uppers has not been so good. I tried the Bushmaster .22LR conversion. Coming from one of the most reputable AR manufacturers, and at the price of around $400, you'd expect the thing to work. This just wasn't the case. The thing would fire and eject just fine, but the thing couldn't feed to save it's life. I don't have any experience with the others that are out there, but the Bushy should have, but didn't, work. :?