The reason I remembered the 5.45x39 bolt action East Germanrifle is because I worked on one some years ago. An old
friend had one of these SSG 82 rifles and had problems with the cases sticking in the chamber, difficult to extract the empty
cartridges. The cartridges had a coating on them and sometimes left a residue in the chamber, this would buildup over time
and usage - and not cleaning. After cleaning the chamber thoroughly, the problem was gone.