This past saturday, a group of us went skeet shooting. One of my friends had a stevens shotgun that was handed down to him by his grandfather. Near the end of the day it started to misfire, about every one is 6 or so then right before we left 1 in 3 shots. I picked up a couple of the unfired rounds, and the primer looked like it had been barely tapped by the firing pin. Any advice on where to look for parts and how to fix it?
Since it was handed down by his grandfather, who knows how long it's gone without a good cleaning. I would start by finding a manual and taking apart the bolt assembly. If it's gunked up in there, or anywhere else for that matter, it would be the exact reason that the firing in isn't moving with enough force.
If a good cleaning doesn't fix it, take it to a gunsmith. If anything, a spring as probably become weakened.
But I'm thinking that it needs to be cleaned first.