I made a bmg mag and 1 single bullet. you have to print 4 bullet for mag with special bottom blocker (Gadget_Empty.stl and Gadget_Empty2.stl have it)
USE GLUE to stick bullets in your mag, if you want use it like a keychain (you know why, to sit perfectly in mag without slack). You can use it like a keychain, fun toy, i.e
Don't forget like my model after download. Happy Printing !