I will hop in here. The ceiner is all set to drop into any standard 5.56 upper without changeing out any other parts. Pull rear pin, slide out 5.56 bolt group,replace with Ceiner unit,close up upper and replace rear pin. It will take you longer to load the magazine than to convert the gun. The only hitch is that some aftermarket trigger systems don't smack the rimfire hard enough to work well. I could never get the jewell trigger to work on the Ceiner system . The RR National Match trigger will work fine with the Ceiner.