Usually I do most of my bp shooting in warmer weather. That being said, I have never had problems with those guns or unexplained misses while hunting.
I took both my 58 and my 12 bore out to do some colder weather testing (teens).
What a mess. 100yd groups over a foot, etc.

I was using TC bore butter(don't judge).
Not interested in reinventing the wheel so would love to hear what works for others.

Thanks

Tom