One of the things I struggle with when afield is keeping my rifle clean and in good working order. Small amounts of dust and dirt collect moisture; moisture can freeze rendering your action immovable when you need it most. I have seen this happen on multiple occasions, and over time, I’ve learned the cause and how to prevent this from happening.
The first thing that you need to avoid before going afield is leaving excess oil on the gun. Oil will trap dirt and sand in all the wrong places. Even though I’ve known folks that spray the entire firearm with a good blast of Rusty Duck or WD-40, this is never a good idea before a hunt. It is my belief that over oiling is the reason I’ve seen actions lock, or freeze up in the winter time. I’ve mostly seen this with pump shotguns.
The most effective thing I have found is to thoroughly clean the entire gun with solvent to remove grease and oil. This includes the magazine follower and spring even if you have a detachable magazine. Sometimes, I use a good blast of carb and choke cleaner; it really does most of the work for you. Once the cleaner has evaporated, you’re left with a clean bare-metal, which is desirable if you’ll be hunting the high plains, or in the “sandbox” where you’ll be exposed to heavy winds and excessive sand. But for the rest of the country, I apply a liberal amount of oil and then wipe all of the oil off the gun with a dry cloth.
In the field, I keep a small amount of electrical tape on the end of my muzzle. Enough to put one layer over the bore and several wraps around for extra after I shoot through it. This does wonders in the field to keep your bore clean.
At camp, or in my pack, I have made a small bore snake out of ball chain and fishing line. It is pictured below. I store this chain and plenty of patches in a film canister (which are hard to come by these days!) the whole thing probably doesn’t weigh an ounce total.
Using this stuff in the field is going to improve the reliability of your weapon. If you’re unfortunate enough to have experienced problems like this before, hopefully this clears them up.