For your price range, I would either get a stripped BCM midlength upper (www.bravocompanyusa.com), add a BCG and charging handle, and buy a Magpul MOE handguard - OR - get an upper from PSA (www.palmettostatearmory.com) and if they don't have have BCGs in stock, shop around. Check out www.arpartsfinder.com if you don't know about it... and unless you're building for looks alone, I would save the money you would spend on a muzzle device and keep the A2 birdcage - there's a reason why our military still uses it. Use the money instead to put down on a better trigger (Geissele maybe?), upper, etc... Good luck.
Good stuff man, but I need to get a complete upper. Im willing to attempt the lower, but the upper intimidates the crap outa me...
And I dont have the tools to try it....
"Character is doing the right thing even when no one is watching"