I was looking at a 6" stainless GP100 today at a local shop. It was used but seemed to be in good shape. I was about to buy it, and something made me spin the cylinder while it was open. When I did, there was a weird rattle as the cylinder rotated. My blued model doesn't do it, and I handled another used blued model they had in the store and it didn't do it either. I asked if they would come down on the price since the guy behind the counter witnessed it, but he said no, so I left it there. There was no endshake or other abnormalities I could find, but I didn't trust it. Any idea if it's serious? I might go back and get it if it's not, cause it was a decent price.