Extraction problems with mod 99 308 win.

I am a gunsmith in New Mexico restoring a Mod 99 in 308 win. After a round is fired, upon working the lever, the bolt moves back a bit and locks up. When cycling unfired rounds everything works smoothly. If I put an unfired case in the chamber it ejects smoothly. If I put a case that was fired in the gun in the chamber, and pull the trigger, the bolt locks up again. I had twenty years as a prototype machinist, so I did a careful inspection of a fired case in comparison to an unfired case and find no difference greater than .002 on any dimension. I had to replace the lever due to sever pitting with a new one from Gun Parts Corp. I would like to know if Mod 99 levers are all the same from the lever pivot screw to the pall that rides in the bolt, or they caliber specific. It also appears that the barrel may have been removed at some point, or a different 308 barrel installed in a receiver that was orriginally a different caliber gun. Any thoughts on this matter would be deeply appreciated, Gary