remixed from https://www.thingiverse.com/thing:3801207/files by @Corn_Flake to fit Hellcat mags better. the original will work but there's a lot of play and i wanted something that fit better.

I used 3/4" drywall screws to mount to the inside of my safe. may need to drill out the front holes with 1/4 bit if you don't have a skinny #2 Philips screwdriver.

I modified the original in Tinkercad. sliced in Cura with Tree supports