The Russian Mosin Nagant Forum

This is what is happening when you try to extract a round.....It seems to function ok with the exception of this issue (Extracted round comes back with the bolt)

hows the ejector /interupter? it may possably be hung up in the wood of the stock to check take the action out of the stock and see if it ejects

That's the first thing I'd check, also. the I/E could be hung up, or held in by cosmoline. If it's not hung up, I'd replace the spring for the I/E (most are a two piece unit; some very old ones are one-piece.). while the I/E group is out, inspect the little 'block' that sticks out. (The actual ejector) If it's worn or 'dinged' in, replace it also. A new I/E group is an inexpensive and easy fix.

Some snap caps would be a much safer bet than loading and unloading live rounds in the house. And fortunately they actually make them in our caliber. How well have you cleaned the area? It has to be disassembled to remove the interruptor/extractor piece that Entropy is talking about just to clean it properly in the slot that the interruptor rides in.