This is a classic symptom of an under-length Mosin-Nagant extractor. I have a rifle that used to suffer from this problem. Here is the diagnosis and solution:
Remove the bolt from the rifle. Hold the bolt up to a strong-BACK-lit light source, looking at the bolt sideways. Look carefully at the extractor's claw. If you can see a sliver of light coming from between the extractor's claw and the bolt head, then your extractor is PROBABLY of the correct length.
HOWEVER,
If you cannot see any light at all between the extractor's claw and the bolt head, then the extractor is TOO SHORT.
I have an ex-sniper M-N that came with a mis-matched bolt. The gun was in excellent condition except that it couldn't chamber a round, except occassionally, with rough handling (e.g., slamming the cartridge into the chamber.....not recommended technique).
A little research with my other Mosin-Nagants turned up the problem.
The easiest/least hassle solution is to replace the bolt head/extractor assembly with another one.
Of course, you can also replace just the extractor, but as many people have probably all ready told you, this is a tricky proceedure (you GENTLY pound the extractor out from the front size rear-ward with a wide (large) drift brass drift punch. It takes a lot of gentle taps. Did I remind you to tap gently? A little penetrating oil applied the day before will help free up the extractor.
If it were me, I'd just buy a replacement bolt head/extractor assembly. It'll set you back about $15.00
Phil-ums