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Bushmaster was notorious for poorly installing front sights during the Y2K buying period. Left-most rear sight position when zero'd on a windless day is a common indicator. That and their infamous Barney the dinosaur purple bushies.
If you really believe the barrel is bent (very doubtful), take it off the upper and remove the front sight. Then roll it around a level surface. You will see a wobble if bent. Or better yet, chuck it in a lathe and check for runout.
However, round impacts scattered between 3 and 6 o'clock positions at 25 yards does sound like operator error. Bench-rest the rifle and properly zero your sights. Only use the 25-yard line to get your sights within range. Move to the 100-yard or meter line to zero in your sights and check what's going on.
My guess is that you will end up with your rear sight adjusted too far to the left when zero'd. That is a very good indication of a canted front sight.
You are somewhat screwed in fixing the cant. The taper pins which hold it are secured in a channel drilled out on the bottom side of the barrel. Good options include:
1- Calling up Bushmaster and seeing what they can do.
2- Replace the front sight with a DCM style front sight that is adjustable.
3- Change out to another type of sight that does not use the channels like flip-up sites from YHM.
4- Removing the front sight and replace with a gas block.
If you traded a 1/7 twist, chrome-lined CMV barrelled carbine with M4 cuts for a Bushmaster 20" A3 barrel, you were screwed. Live and learn, and never trade without shooting first.
ETA: also check your crown as it could have been messed-up with poking by a JAG.
If you really believe the barrel is bent (very doubtful), take it off the upper and remove the front sight. Then roll it around a level surface. You will see a wobble if bent. Or better yet, chuck it in a lathe and check for runout.
However, round impacts scattered between 3 and 6 o'clock positions at 25 yards does sound like operator error. Bench-rest the rifle and properly zero your sights. Only use the 25-yard line to get your sights within range. Move to the 100-yard or meter line to zero in your sights and check what's going on.
My guess is that you will end up with your rear sight adjusted too far to the left when zero'd. That is a very good indication of a canted front sight.
You are somewhat screwed in fixing the cant. The taper pins which hold it are secured in a channel drilled out on the bottom side of the barrel. Good options include:
1- Calling up Bushmaster and seeing what they can do.
2- Replace the front sight with a DCM style front sight that is adjustable.
3- Change out to another type of sight that does not use the channels like flip-up sites from YHM.
4- Removing the front sight and replace with a gas block.
If you traded a 1/7 twist, chrome-lined CMV barrelled carbine with M4 cuts for a Bushmaster 20" A3 barrel, you were screwed. Live and learn, and never trade without shooting first.
ETA: also check your crown as it could have been messed-up with poking by a JAG.
what twist is it again?
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