So I'm going to get a 10mm upper and a dedicated lower.

Is there any way I will be able to use something other than the UZI mags? Like some mags that are plentiful and cheap?

Also is there a way to make it so you dont have to have a brick attached to your mags, but instead modify the AR lower permanately somehow?

Cav-Arms plastic lower and M3 mags (that give you approx 35-37 rounds), or wait till the Cav-Arms aluminum lower comes out that will accept M3 mags.

Quoted: Cav-Arms plastic lower and M3 mags (that give you approx 35-37 rounds), or wait till the Cav-Arms aluminum lower comes out that will accept M3 mags.

Any more info on this aluminum lower? Do the mags need to be modified?

Just contact Cav-Arms... I think the Mag will require a cut so the AR style mag catch will retain the mag.

No need to cut a notch.  The Hahn mag block utilizes an "M14-style" release that works with an unmodified M3 mag.

Quoted: No need to cut a notch.  The Hahn mag block utilizes an "M14-style" release that works with an unmodified M3 mag.

OK, that'll work.

Quoted: No need to cut a notch.  The Hahn mag block utilizes an "M14-style" release that works with an unmodified M3 mag.

Can you provide some more info on this? Google wasnt much help.

ComputerGuy, I just put a Cav Arms Mark II lower under a 10mm Olympic Arms upper. I was at the range yesterday and it ran without a hiccup. I used a bunch of 175 grain lswc hand loads that I had. I use the Hahn mag block, the heavy buffer and gently adjusted the mag lips of the grease gun mags with a brass hammer, just until the 10mm round would not pop up out of the feed lips. I wasn't sure how I would like the Cav Arms lower but I am really liking it, I don't see any need for an aluminum lower unless you want to attach a different stock. I can get 36 rounds of 10mm in the grease gun mag and it doesn't have to be modified with the Hahn block. My email is [email protected] if you have any questions. I have been to the WAC show and found grease gun mags for $5.00 and $10.00 each. David

Where can I get a Hahn mag block??

Order through Brownell's. David