My normal lube procedure Is clean and coat with some kind of CLP - this time was Rem Oil. After about 10 min or so I wipe off excess and apply a few drops of hoppes gun oil to the rails. Done Same with the 500 - CLP and a drop of oil here and there.
Neither of those guns should have a problem at 20 degrees F. No experience with Glock but I've fired my Mossy 500 at -10 and SR40c at -7 this AM.
I have had problems with Rem Oil though in below freezing temps even with very light coatings. It is also very easy to use too much Hoppes in cold weather. Switching to ATF has eliminated cold weather issues on all my guns, even a finicky .22. FTF is probably due to too much lube on striker / firing pin and having it gum up from cold, it don't take much. I would wipe off all CLP before lubing rails and slides with ATF. Firing pins can run dry but a very light coat of ATF, either wiped on or blown off will be OK. I never put a drop of any lube on firing pins any more, it's way too much.