I have a Bushmaster M4 Type. It is "post-ban". I do not care very much about the lack of bayo lug... although I would appreciate one for the novelty aspect of it (plus the hot babes at the range think bayos are cool). But seriously, would I be better off (from a cost and performance standpoint) (1) sending the upper to Bushmaster in Sep (or another well qualified smith, recommendations please) to have the mini-Y and sight block removed and in their place have installed one of the very nice Yankee Hill hiders/comps and floating forearm kits or (2) just selling my existing upper to someone in one of the states where "post bans" will continue to be banned and buying a whole new upper set up the way I want it (with hot babe magnet bayo lug)? I guess the essence of this question is, how much is my well maintained post ban Bushmaster M4 Type upper with Mini-Y comp worth?

Thanks in advance for the feedback!

Just buy a new barrel, barrel wrench and upper vise thingy,   and just replace the barrel.  That seems to be an option some people think is impossible or something.  Takes like 30 mins or less to change barrels on uppers!  complete upper cost- 400or so,   barrel cost and use your upper- 150+    which one sounds better to you?

Noted. Thanks. However, I failed to mention that I have a phobia about head spacing or doing anything related to my M4 that could cause it to not work properly. But let's say I do buy a new barrel and have a qualifed smith do the work... any idea how much my old barrel would be worth? Assume it has been maintained as per manual specifications and has had less than 2,500 rounds fired through it.

Quoted: Just buy a new barrel, barrel wrench and upper vise thingy,   and just replace the barrel.  That seems to be an option some people think is impossible or something.  Takes like 30 mins or less to change barrels on uppers!  complete upper cost- 400or so,   barrel cost and use your upper- 150+    which one sounds better to you?

The headspacing is fixed at the factory when the put the extension on the barrel, you don't adjust it.

If you can follow simple instructions, have a vise and a torque wrench and some moly disulfide based anti-seize for the threads and some vise jaws to holt the reciever, you can easily change the barrel.

The only headspace work you really need to do is to get a field guage to check for excessive headspace.

For a smith, check out Kurts Kustoms in the Industry section.  I want his A3 flash hider on my sept special M4gery.