Definitely very strong in terms of DPS, lol. I made a local copy and played with the stats, maybe you can consider these changes:

Raise "Reload" in rangedweapon element to "0.5" so it fires just a little slower than the Autoshotgun.

Increase skilled spread to 8, to overshoot the Autoshotgun by just a little bit.

The rest of the gun is pretty fun! Expensive to handle, but as long as you have enough shotgun shells to feed the drum then you're pretty much unstoppable. As a side effect of increasing the reload, the ammo consumption is more controllable and thus one full load will last significantly longer!
I personally enjoy how the weapon can't be crafted. It forces you to find or purchase this endgame-oriented weapon.