I'm tired of my A2 upper and the mini y comp brake on my Bushmaster. I'm thinking of purchasing ($159) a Bushmaster flat top upper (which comes with forward assist and ejection port cover) and having Kurt at KKF perform the following work for me.

1) remove the mini y comp and replace it with a KKF A3 tac brake (fake flash suppressor for $90 installed.)
2) Remove the barrel from my A2 upper and install it on the new A3 upper (gunsmith charge unknown).

I figure this modification would in the end be cheaper than buying a whole new complete A3 Bushy upper ($400), and then having KKF remove and replace the mini y comp brake ($90 installed).

What do you guys think of the feasibility and economics invovled in the changeover. I could care less about waiting for the sunset of the AWB next year and replacing those featues. I know I should have bought the A3 Bushmaster M4gery in the first place. I can't afford to buy another AR to rectify my previous decision.
I figure the entire cost to be at or near $300.
What do you think?

You get a receiver and a lot of work done. Aftermath: $300 spent and one functional upper (of your chouce)

You get a complete upper of your choice. Aftermath: $400 spent and 2 complete uppers.

$100 extra for an entire other upper? No contest! Throw in another $300 down the line when you come into the money & you have a second complete AR.

I would say to just sell the upper you have, and then buy an entire new upper assembly from Bushmater. Get a PRE ban one. Then take off the flash supressor, and send the upper to Kurt to install the brake. That will save him a little time and work of not having to thread the barrel. He can also remove the bayo lug as well. That how I did my cqb carbine. He did such a good job(as usual) that it looks factory.

That said, your idea is not entirely bad at all. Definitely feesable.

If you are changing out uppers, why buy a complete A3 upper?  If you get a stripped one for $129.00 you could have your forward assist and ejection cover put on from your older upper.

BBetter yet, you can get a mil spec flattop upper WITH RAS numbers on it for $89.00 complete in the Equipment Exchange.

What's the difference between an A3 & A4 uppers?

What's the difference between an A3 & A4 uppers?

A3=flattop designation by Colt, Bushmaster, DPMS

A4=flattop designation by Armalite and Rock River Arms.

They mean something completely different by the Military.