Before mine was lost in the lake, I really enjoyed it, I had to play with buffer weights and springs to get it to run well at speed, but once I got it setup right it never had any issues. Mine was installed on a 10.5" no name build before I lost it. I also got mine on sale I think it was around $300. I wouldn't pay $400+ for one, though because its not something you can fully utilize shooting at a public range that doesn't allow rapid fire. They are fun as heck though no denying that, and if you keep your bursts short (2-4 shots) they will stay on target fine, but I'd have to buy more ammo to be able to get accurate on longer bursts.