I recently purchased a Russian 91/30 Mosin Nagant, year 1942. The rifle cycles live rounds beautifully. I don't have the "sticky bolt" issue others experience, especially after removing the bolt and cleaning the rifle. However, after firing a round, the extractor fails to remove the casing from the chamber. After removing the casing, the rifle continued to cycle live rounds perfectly but for every single round I fired, the casing found itself stuck in the chamber. The bolt opens fine, but the casing stays up in the barrel. Does anyone have any ideas as to what would cause the extractor to fail after firing the round, when it works perfectly fine beforehand?