I have had a Remington 870 Express in 20ga for about two years now, although I only recently began to shoot clays with it. Anyways my question relates to extraction of the shell, it has happened to me three times know and as this gun also double duties as my HD gun I am pretty worried about it. What happens is the shell just plain fails to extract, the extractor is either jumping the rim of the shell or tearing through it. What I am wondering is what could be causing this? Also what can I do to fix this?