[xenophobe]

This isn't a malfunction, it's a design feature. It's not the chamber that is keeping the round seated, it's the fact that the bullet is seating in the throat (the transition from chamber to rifling), and is actually wedged into the beginning of the rifling. On a match-grade chamber, this is normal. Finding the right ammunition might help.

 

[xenophobe]

This is a situation fire-lapping your barrel might actually improve. Since there will be considerable buffing/polishing of the throat, it might help to keep bullets from being lodged too tightly into the throat... just a thought.