Some USGI mags I'm using for parts replacement. The body has been spray painted. Anyone have recommendations for stripping off the old re-painting/re-coating with new?

Sand blaster is the fastest and safest way to remove the old paint. You can get a el cheapo sand blasting setup at harbor freight if you want to do it yourself or find a local metal or paint shop where the guy would probablly do it for a ten spot.

Degrease throughly, then finish with Gunkote of your choice. Reassemble and spray a little dry lube inside the magazine. Test for function and you are good to go.

A local shop is probably the best way to go for me. I wonder what coating I should use or have it powder coated?

Don't sandblast - aluminum body. Wash air-dry paint off with paint stripper. Use a bake-on coating to re-coat. You don't have to do any sanding or blasting after using the stripper - it'll be clean enough. Brownell's sells several kinds of bake-on (oven-cure) products, and the 'Dark Parkerizing' color is the closest to the original finish.

I just tried this yesterday on a mag....sandblast the old paint off....place in a welding rod oven(I'm at work) to warm up the mag body...spray a dry moly coating inside and outside the mag, put it back in the oven for several hours to cure out....turns out grey.  The blaster was a very, very small one and it took the paint off very well.  Not sure why I shouldn't blast the mag??  It was very fine "starblast" sand...anyway...I tried it on one mag just to see what would happen.  Think I will have to try the bake on finish also.  Just trying different things.

I sandblasted my aluminum USGI mags with no ill effect. Why is this a no no?

It's only a no-no if you use the wrong media and/or to much air pressure.  I have recycled auto glass in my blast cabinet.  I turn down the pressure till it will just take off the finish and still pick up the media.  Does an excellent job, can't tell it's been blasted.  Brownels is the place to get the recoat materials.