Which 9mm upper?

[swiftytheavenger]

Hey, I picked up a completely built lower that the old owner had on a .40 caliber upper. I have lots of 9mm stocked up and Im looking at the Rock River uppers at ADCO. Will these run anytype of mags? I see all sorts of metal mags, uzi mags, c product mags etc. And I dont know if they'd run in this setup.. And if they did would they feature the bolt hold open/release?

Thanks for helping out the new guy in advance!

[TinMan556]

I like the RRA uppers

[chris914]

I have the RRA and C-Products mags have been finicky at best. It is a winter project.

[High Tower]

I have the RRA upper. The type of mags you use depends on the lower and the type of magwell block unless of course you have a dedicated lower. Mine is set-up to use un-modified Uzi mags with the VM-Hytech (I think) block, but I cannot use any other mags. There is no bolt hold open with my set up. And the mag release button is in a different place.

ETA: My setup has been very reliable. The only time it has jammed (3 times in 720 rounds) has been due to lack of lube.

[Mega]

The type of mags you use depends on the lower and the type of magwell block unless of course you have a dedicated lower. Mine is set-up to use un-modified Uzi mags with the VM-Hytech (I think) block, but I cannot use any other mags. There is no bolt hold open with my set up. And the mag release button is in a different place.

My upper started life as a stripped CMMG and has a CMMG bolt.

The lower is an M&P15 with a VM Hy-Tech mag well adapter.
http://www.brownells.com/.aspx/pid=1..._BLOCK_ADAPTER
It uses un-modified Uzi Mags and has been stone reliable.

[devinsdad]

Lots of folks bust on the CProducts mags, I've never had a problem with them. Can't see throwing good money out for Metalform mags when I can get 2-3 for the price of 1. The upper won't know what mag you got running as all the major parts are in the lower.
Good luck!

[Fried Chicken Blowout]

I had a dedicated complete 9mm RRA Car-9 with the 9mm only lower... It would not run the C-Products or ProMag mags at all. The C-Products were the worst. I tried 20 of them and could not get any of them to be reliable. The ProMags would work, but the feed lips would break after about 200 rounds through the mag. The "factory" Uzi mags worked great but didn't have the BHO on the last round. I sent back all the C-Product and ProMags and got my money back and then sold the rifle with the Uzi mag. It would have been a fun gun if it ran. I was totally pissed and disappointed.

[KalashniKEV]

Another vote for the VM-Hytech. It was a bit of a pain to open it up for 32s, but mine has been ROCK.

[glock19.com]

My RRA 9mm ( complete from factory 9mm rifle) is fantastic with Colt SMG magazines

the converted UZIs that RRA sells are pretty shoddy IMO might just be my particular rifle but they are hard to insert and seat , and make the mag release tough to push
I received one with the rifle and bought another they both do it

have about a dozen C products they work well but the older Colt SMGs mags are smoother in and out of the magwell , and the mag and bolt release work much smoother with them
Couple of the C products were finicky but smoothed up and broke in with use and now work fine

[mike benedict]

I have a CMMG 9mm upper that runs great.
for a lower I have a RRA with the Brownells 9mm kit.
When I got the upper I asked CMMG what to do for a lower and they told me to get the kit from Brownells.
I have 10s of thousands of rounds through this carbine with out issues



Stock #:080-000-442AR-15/M4 9MM LOWER RECEIVER CONVERSION KIT
Drop-In Kit Converts A Stock Lower Receiver To Accept A Sub-Caliber Upper