Yes, I did get Smitty to upgrade it! I had almost forgotten about that. It really helped in the final battle, because I had accrued 10 action points, and it only required 4 to fire it after upgrading, which let me step back one after firing. I can't remember where I found it - in the Glow, I think.

My aim must have terrible! I did notice that if I hit a baddie just right, they melted into goo, but most of the time they took 30-40 damage.