You are very correct on the lubricants. It was only 0 a couple weeks ago when I was out. Somehow I let too much oil into the bolt I guess. I could not close the bolt on my ammo - the exact same ammo I have been running thru the action all fall without finding anything to shoot. I could close the bolt on an empty chamber so snapped the trigger. After that I could chamber the ammo. I have since dried out the bolt more. I might have had some snow or condensation somewhere in the chamber or bolt too but couldn't see it.
A lot of folks carry a light pump 12 ga with slugs for bear concerns. They seem to withstand bad weather and crud very well, are pretty light and very reliable and relatively inexpensive.
I have 2 friends who have dumped charging bears with bolt guns. One had the gun knocked out of his hands at the shot. He carried a Win M 70 .338 shot from the hip. The other had a Weatherby Vanguard 30-06 the 2 times he was charged. Deflected one bear, enough for a second shot, dumped another with the first shot at 20 yds I think.
Both guys were very handy with their rifles.