There are a lot of 21's out there. Be patient and look at as many as you can. In other words don't buy the first one you find. I'd make a list of all the features you want in the gun. Then decide if some are deal breakers or just gravy. I'd like two triggers but others will go two or one just the same. If you are interested in BTFE make sure where it is attached has no play in it and the hanger must be secure. BTFE have been known to pull off under heavy use. Enjoy the search.