I have a Pre-ban Colt A2 that I had sent the upper out to have a Bushmaster 14.5" barrel installed onto (permanently attached FH for 16").

I read somewhere that the A2 sights sit higher than the M4 front sights. Also read you had to replace some parts in the rear sight to get it to level out- that these parts were available at Brownell's- anyone have experience with this issue and what exact parts need to be swapped.

BTW it shoots fine but I only shoot at little ammo boxes and clay pigeons and have never actually tried to paper shoot with the thing for all I know it could be shooting high or low- probably whatever the A2 versus M4 would end up with.  

The difference is the [u]Colt M4[/u] barrel. Since you had a Colt A2, then added a [u]Bushmaster[/u] M4, you *should* not have any issues.[;)]

So this is an issue only with Colt M4 barrels, not Bushmaster. SO basically Bushmaster uses A2 Sights with their detachable carry handles??