You can get a longer mag (mag without those case stops at rear) from midway or brownells. I forget which one I bought mine from. Then you can also trim the bolt stop shoulder on the inside almost to the little web piece molded on the inside. I used a hand hack saw and very small file. That allows the bolt to slide back further to catch the cases that now sit back further. You can do a google search and find pictures and articles about this mod. Hope that helps.