I found a new complete upper for $350 without the magazine. I imagine it was robbed from the kit when the magazines were selling for big bucks. I know

black dog mags are compatible. Are there any others? I am thinking s&w mags might be easier to find around town . Thank you.

The SW 15-22 mags are the best I have found that also gives you last shot hold open with the better mag adapter.

I really like the Black Dog drums too. But no last shot hold open with those or the standard Black Dogs either...

Smiths are the best straight mags hands down in my opinion..Easy to load too..100% reliable. Great looking also.If that is important to you.

The SW 15-22 ones will work without the adapter but are too loose fitting in the lower for my tastes so we use the adapter.

Obviously, CMMG magazines work as well, as do original Ciener pattern steel magazines.