We used "Spit Patches" for many many years. A spit patch will work great, however you need to shoot the ball out every day or you can get a small rust ring-I did not like this idea so I switched to Bore Butter.

Any grease product is going to thicken a bit in the cold weather-that is just the nature of grease. Give it a quick rub between your fingers, or put it on the patch and rub it in(or a snuff can already greased). It would be alright to make some-but I have just never been motivated to do so. But then I am not thepurist type. If I was then I would use bear grease.Tom.