a-5 flatline crooked

i don't know, i didn;t have this problem. i assume that you are holding the barrel somehow while you tighten? get all the bolts in place, then tighten them slowly, a little at a time alternating. don't crank down on them one at a time. and hold the barrel inbetween your legs. i put mine on while it was on the floor. also, get the bolts as tight as possible and still be able to move the barrel around. then, when it moves, put it back into position and tighten the bolts as i said above. hope this works.