my grandfather gave me a DPMS LOPRO 16 w/ bull barrel.. was wondering what kind of rails i could mount on it.. yes, i know it's a bull barrel but i like the bull barrel feature.. i'll prob get some quick disconnect mounts from larue tactical and get a red dot scope for building entry/executive protection and a typical hunting 6x24 scope for varmints.. but, i still need a light and want a vertical grip.. so, can you guys help me out w/ the rail system?? i'm confused as to if i can put a normal rail system on a gun w/ a bull barrel..