I was just curious what mags owners of 7.62 AR-15s have and would reccomend?  Also where do you buy them at?  

Well, I don't have a 7.62 AR yet, but I'm buying the hybrid mags.  They look like a regular 223 mag w/ an AK 47 bottom welded on.  The only mass(?) manufactured of this type was by USA mags.  Yes, I said USA mags.  The ones that everyone says has cheap mags that don't work....well, their 7.62x39 AR hybrids do work.

High capacity 7.62x39 AR15 magazines are getting harder to come by and usually more expensive when they are found. Keep an eye on the Equipment Exchange, the usual firearm auction sites, local gunshops, gun shows, etc. Basically the same place you find any other firearm accessory. It's just kind of hit and miss as to where they will turn up. I can't think of any guaranteed sure fire sources. If you find reasonably priced ones, grab 'em. If nothing else, they are hot sellers in the Equipment Exchange.

I will second the recommendation for the hybrid style magazines. The USA ones, models EXC133 and EXC133A, are the most common and affordably priced. While being constructed a little on the cheesy side with aftermarket parts spot welded together, they do work well and the follower has a bolt hold open provision that actually works. My personal preference are the G-Tech and Scherer ones, however. These use a genuine AK-47 magazine body, spring, and follower with an aftermarket steel AR15 feed tower TIG welded on. They are very durable and tough as nails, hell I could probably drive nails with them. Their only drawback is that the AK-47 follower won't hold the bolt open after the last round, but this is an extremely minor inconvenience for the over robustness of the magazines. Unfortunately, they are now very difficult to find and often twice the price or more of the USA versions.

As was also mentioned, USGI magazines will also work with the 7.62x39. The only catch is that you can only get about 6 or 7 rounds of 7.62x39 into a USGI magazine before the more extreme taper of the 7.62x39 cartridge begins to cause them to bind up within the magazine, swell the sides of the magazine out, and lead to feeding problems.

There are also post-ban magazines that seem to work well. One that comes to my immediate mind is the MWG polymer 10 round magazine.

I've followed others' recommendations to stay away from the 20 round 1 piece style 7.62x39 magazines, so I really can't comment on them other than to say that I've yet to hear anything good about them.

For reference, here is an image representative of some of the various 7.62x39 AR15 magazines in my collection:

[img]http://photos.ar15.com/ImageGallery/Attachments/DownloadAttach.asp?iImageUnq=3215[/img]

Top row, left to right:
MWG 10 round post ban
Colt 5 round post ban
Colt 5 round pre ban

Bottom row, left to right:
Scherer 30 round hybrid pre ban
G-Tech 30 round  hybrid pre ban
USA 30 round hybrid pre ban Model EXC133A
USA 30 round hybrid pre ban Model EXC133 (This magazine was packaged and labeled as a 30 round magazine but in fact will hold 40 rounds)