A roommate I had once got an old .22 rifle once, and took the surface rust off the barrell with 80 grit sand paper, and he lost the sights. I could still hit anything I wanted too with it, without the sights. That torked him off a little, but then his 80 grit trick did me too.
What gives you the best results for pumpkins in a 12 ga.? Buckshot, or slug? (I never been pumpkin huntin' ) I thought I'd show them what my .308 does to a coffee can full of water with the lid on, and a coffee can size block of ice. That's allways impressive.