If I am understanding you correctly, I used to snug tighten the 2 end bolds, then use a beater to square up and set at the required dimension, snug the rest of bolts and then use the gun, it always worked well for me, but i have also worked alot of shops where you only send them out in the snug tight condition! The place i work now sends all clips loose, we don't do any bolting at all in house!
Hope that helps you!
Carl