Ok i really need your help so please bear with the long question.
I've got a Bushmaster with a 20" Stainless steel barrel A2 upper. I'd really like to have a carbine AR as well, or preferably an M4. Now, in the interest of saving money, i'm thinking about just getting an M4 A3 Upper (prefeably with a flip up front sight). Is that advisable? also I read that i would have to get a new bolt carrier, since interchaning them may cause the rifle to expolde, have you ever heard of this? Which upper should i use, or better yet which ones or brands should i NOT use? Or should i just get a new M4 All together? i liked my bushmaster, but what would be better/as good for less?
I want to really trick it out. any suggestions or perhaps pics?
Thanks alot everyone!

If I were you I would get another upper.  Get a postban flatop M4 14.5" with a muzzle brake that brings it to 16".  If the AWB is not replaced, send the barrel to Kurt and have himn install a phantom flash sup or similar flash sup.

If/ when the ban ends, you should have also saved a bit more cash, so you should be able to buy another lower that will allow you to have the adjustable stock.

Whatever you decide, I gotta say steer clear of flip up front sights unless you're building a *really* specialized rifle. Not enough benifit for all the fuss. I don't notice the front sight using a scoped flat-top even when dialed down to 2.5x.

> Get a postban flatop M4 14.5" with a muzzle
> brake that brings it to 16". If the AWB is not
> replaced, send the barrel to Kurt and have him
> install a phantom flash sup or similar flash sup.

not to step on anyone's toes here but you could also order a "blunt" bushmaster full 16" M4-profile flat top A3 upper through Chris at Eagle Firearms (see the EE).  and get it for less than bushmaster's catalog price.

that's what i did, and i could not be happier.  i've got a full 16" bbl, no loud brake, and if the AWB does sunset on schedule i have a whole host of options.

ar-jedi

edited to add: note that the pic below is an A2 but same barrel config is available in A3 flat top as well.  click on the bushmaster link below the pic.

BUSHMASTER CATALOG NUMBER PURA2B 16M4:
[img]http://bushmaster.com/shopping/uppers/Images/pura2b16m4.jpg[/img]

[url]http://bushmaster.com/shopping/uppers/post-ban/pura2b16m4.asp[/url]