I bought one in the 70's, (I could not afford an AR15 at the time)  I could never get it to shoot well, tried several brands and different reloads.  I could shoot 1 group about 1-1 1/2 inches, the next group would be about 5-6 inches!  I have been told this is not uncommon with these because of the hunk of steel that moves under the barrel (opperating rod).   I now have 3 AR15s.  Watch out for BRD! 
