I have often found that completely disregarding the price will sometimes help. The owner and I both know that MSRP means nothing in there. I'll go in, find a bin full of Craftsman sockets, pick out the ten or so that I need, and pitch them on the counter with the words "make me a price." The bin was marked 25 cents apiece, but he'll give me these dozen for two bucks. Those sockets came in to him at five bucks for the 50-piece set, so he's in 400% profit land and I just bought $20 worth of tools for $2.
I've never tried it with guns, but I suspect that it holds true. By the way, military towns are a great place to go pawn-shopping. Except Leavenworth, KS. I found a whopping one pawn shop there, and I watched the owner buy a DVD player from three guys who might as well have been wearing big day-glo orange nametags that said "BURGLAR." The thing still had part of the coax connector on it. I guess an almost complete lack of enlisted men makes for slow business at a pawn shop.