I'm not sure if this is exactly the right place for this question, but we'll see. I've got a few shells left from the last box of turkey shells I bought. 12 ga. Remington Hevi-shot, 1 1/2 oz. of #5, 3" shells. They were bought in 2003 (I've still got them because of a combination of having relatively few chance to hunt turkeys in the last few years, and the fact that I suck at it from lack of experience).
Anyway, today I was checking my gear and found this white, sandy, granulated stuff leaking out of the crimp in my shells. I shoot a Remington 11-87 and just cleaned it a couple of weeks ago. However, when cycling shells through the action, this grainy stuff wound up all inside the action and kept the shells from cycling cleanly; I had to nudge the bolt handle to get it closed on the new shell. I haven't had this problem before.
I cut open one of the shells and found this grainy stuff mixed in with the shot. I'm not much of a shotgunner and don't reload, but it seems like it might be messing with my action a little bit. I'm gonna buy new shells, but I was really curious what this stuff is. Is there some kind of wadding or something that breaks down after a few years or what? Thanks!