I'm building my second lower and on one of my lowers both magazine catch fit but the on the other lower the magazine catch is a bit too wide. the lower is a Delaware Machinery and the lower is off a Rguns lower parts kit. needless to say this build is sort of on the cheap. I'm wondering did I get a out of spec lower or sometimes you need to file the magazine catch down to get it to fit? thanks everyone ! Wanna kill these ads? We can help!