This is a mag holder for the Hammerli tac R1 ar15-22LR. Mags slip in from the top and the back side of the mag towards the bracket mount. This mag holder holds 5 mags and should work with the following 4 guns because they use the same mags and are also produced on the same production line by the same company.
1. Hammerli Tac R1 2. HK 416 22LR Clone 3. HK G36 22LR Clone 4. Colt M4 22LR
I would print with 25% to 50% infill or higher if you like.