I recently purchased a Cali complaint AR-15 thinking that the only differences was the 10 round mag. Unfortunately that is not the only difference. They also require the rife to be out fitted with a bullet release instead of a mag release(stupid, I know). I called my local gun smith thinking there was an easy solution and the idiot told me I had to replace the entire lower unit a $300 fix. I refused to believe that and called S&W and the gunsmith told me that is ridiculous and there is no reason to replace the lower unit that I just need to have a gunsmith drill out the bullet release and equip the rifle with a mag release. A 15 min job max. I took rifle to a different gun smith and now my AR-15 with a purchase a standard mag is now a standard AR-15.