[Jack19]

Does someone make a 9mm AR variant that uses Uzi mags? I would have sworn I read about it somewhere but now can't remember where or who the maker was.

[Langenator]

The Colt and RRA 9mm carbines use modified Uzi mags. IIRC, the modification is a cut out to accomodate the AR lower's mag catch.

Both still require the use of a mag adapter block.

Bushmaster may also use the same system, but I'm not sure.

[AJAX22]

you can also modify Sten mags to fit. and they are super cheap (or they used to be)

[LA_Shooter]

with the VM adapter block you can use unmodified mags

[billwiese]

The Olympic Arms 9mm AR uses Sten mags.

Colt 9mm ARs use proprietary magazines. Converted Uzi mags ("3-way" mags - Colt 9mm AR, Uzi and one other - Feather AT9??) can kinda-sorta work but don't expect great things.

The Uzi mags are slightly narrower width than true 9mm AR mags, and can rock a bit in the mag adapter. (Perhaps someone will make a 9mm AR mag adapter for true Uzi-width mags.) The Uzi conversion mags also do not have a special follower (nor rear track for that follower to traverse) allowing bolt hold-open on last round.

There may be some feedlip differences too - I recall loading my converted Uzi mags and after jiggling them ending up with 32rds of ammo in my lap. The Colt mags seem to not do this.

Converted Uzi mags may well have a poor job of the mag catch being cut out, and/or it not being positioned in just the right height. Most of these conversion mags are made by crap makers like USA, Precision, PMI, etc. - co's not known for great mags in other areas either (would you use a USA vs a USGI AR15 5.56 magazine???) If you are using a mix of Colt and aftermarket Uzi 9mmAR mags, you might have problems with the seating height of your mag block and might have to do some Dremel work on your Uzi mags to get them to work properly...

You are better off getting true Colt 9mm AR mags for your 9mm AR upper (providing it's not the different Oly Arms system) - CDNN sells them.

Oh, BTW: don't use anemic ammo in a Colt 9mm AR, or you'll have a jam-o-matic. These guns like hotter loads: PMC 115 & 124gr 9mm ammo just wouldn't cycle, unlike IMI ammo. And these guns are really happy with 147gr black tip ammo ;)

Bill Wiese
San Jose CA