Well, mine worked right out of the box, (don't forget to fully seat the magazine and pull the charging handle) A load of fun for sure. Eats BB's and CO2 cartridges very quickly, good thing both are very reasonably priced these days (I remember my first C02 pistol, probably around 1988, there was no such thing as a 40 pack of cartridges for 20 bucks! It seems to be a full scale M-16 but with an 11" barrel (which I really dig) I think I'll finally pull the trigger on that SBR tax stamp and build my next AR exactly like this one. I've got boxes full of AR accessories that I've used on previous rifles, so mine got a tactical illuminator, a reflex sight, and a vertical foregrip and a tactical sling. I'll try to post a pic.