i have a very similar setup with no bull barrel, factory dpms 16inch with a scope, wait for the wind to calm before you fire your group, start at 50 yards and shoot two groups, repeat at 100 yards and compare, if you see a big difference keep in it mind when shooting at 200 but like others said you should be really close, key is waiting for the wind to calm before shooting those groups, but i will tell you this even with 7-10mph crosswind you shouldnt be off by that much, the idea here is to also check your scope and shooter for errors so that we can further help you, hopes this helped, it really helped a friend at the range i ran into.
and try a different load, what ammo you using? even the winchesters from walmart do really well if you do your part at 200, il shoot some groups and post them tommorow.