Ah well, it should still go bang and be fun. Heavier ammo tends to work better for small barrels. Open tip, hollow points, soft points, bonded soft points will do a bit more for defensive or hunting purposes.

And for the sling, do you know how you’ll mount it in the back? You could replace that back plate with one that has a QD mount. I think there are clamp-on options too. IDK there’s probably other creative ways.