Lots of good ideas here. Only thing I can really add is being anal about your cleaning and de-greasing prior to loading. I swab the bore with alcohol and use pipe cleaners soaked with same to clean and dry out the flash channel under the nipple. I think more miss-fires have been caused by sludge in the flash channel than wet powder. A good tight fitting cap and bullet will keep out pretty much anything short of a dunking but shielding the lock from rain or snow and sealing the muzzle is still needed. You're right about the condensation, once the rifle gets cold keep it cold. If you uncap the rifle, immediately seal the nipple from atmosphere. I lower the hammer on a piece of inner-tube but other material will work also. Good luck chasing the deer with your caplock, good fun!
