'Kerz' - Try using Seating Die to push bullet into case, slightly, to break 'corrosive bond' between bullet and case mouth.

Then pull bullet with collet or inertia puller.

Polish bullets in vibrating Case Cleaner.

Clean case mouths with brush & case lube and wipe dry.

I would toss the powder. I suspect bullets bonded to case mouth or deteriorating powder may cause higher pressures and velocity in this old commercial ammo.