Who makes 9mm flat top uppers? I own a Colt 9MM with the A1 upper and would like to change it out with a flat top upper. Thanks for input.

You want a Rock River Arms 9mm upper.  They are very high quality uppers and I would rate them as well as or better than Colt.  Check out their web site.  I own several 9mm AR's with RRA uppers and they are great.  Greg.

I'd Second RRA 9mm uppers.  Have had no problems, and the specs and finish are great also.  The only thing I can't understand is why a flat top costs more than an A1 upper??? Anyways can't go wrong with RRA.  Check out Pete from LegalTransfers in the EE thats were I got mine.

I HAVE A  COLT LOWER MARKED 9MM,NO EXTRA HOLES,MADE  JUST LIKE A 556 LOWER.I DONT HAVE A BLOCK WITH IT.I WANT TO USE A RRA UPPER.WHAT TYPES OF MAG  BLOCKS WILL WORK WITH THIS SET UP?(MAGS THEY TAKE,PRICE,ETC)THANKS!

Medic, I'm piping in again in case I wasn't clear in the other thread.

Run a RRA mag block($120 ish) , with Colt mags, assuming you are OK with $60+ mags. Or run it  with modded Uzi mags available from RRA through ADCO or RB precision, amongst others, for around $35. You can buy UZI mags and mod them to fit, about $10. This is relatively easy, but not for people without the right tools. The UZI mags are obviously much cheaper, but they don't actuate the bolt stop.  M60Joe can mod your UZI mags cheap enough to undercut the RRA price significantly. The RRA (Colt, etc.)  mag block has the bolt stop capabilty, but the UZI followers won't  trip it, unless you pay M60Joe to fix your followers too.

Otherwise, buy the Hytech block($150 ish) and run stock UZI mags.  The Hy-Tech will not actuate the bolt stop no matter what.  I think they also won't work with Colt mags.

Your lower will take any mag block. I'm still befuddled that you got a Colt lower without the mag block, or at least without the pin holes.  Somebody must have converted that to 5.56, and although I've heard they exist, I've never seen a Colt without the mag blocks pinned in.

I wish I had a Colt 5.56 LEO lower to trade you.

thanks! now its clear.i bought it from a police dept,police officer said he sold the block.im gonna go the rra route with colt mags.its gonna be around christmas before it goes together .