A bit of help please...

I have a Mosin Nagant...
When we got it it fas SOAKED in grease so we had to clean it.
After we got it cleaned up we test fired it...it fires...
The problem...the bolt tends to stick and is hard to open with a shell or round inside it....
When we get it opens...it does one extract the round from the chamber and eject properly...the round gets stuck in place...there looks like a piece missing from the bolt (the second piece that holds the back of the bullet in place on the bolt) I'm not sure if that is how it's made or if I am right...if anyone can help me I really could use it!

i dont know any thing about mosin nagant nor am i any kind of gunsmith lol but i had a problem like that with a recent ar-15 build and it was a dirty chamber mixed with a bad spring on the extractor of the bolt hope this helps

Seems to be the neck of the shells are getting expanded and bent...possible overloadedshells...oris it the rifle?

not sure sounds like it but idk could try a lighter load or some thing might try calling a local gunsmith for an opinion