When I was working as a full-time gunsmith, I had more than a few customers each year bring in rifles that "didn't go bang." Even though I now spend my time writing, researching, shooting and hunting, I recently had two old customers track me down with that complaint. You may be thinking, "They didn't clean their bolt. Big deal." Actually, they had. Or thought they had. One customer missed a large cow elk, and the other had to watch a good-sized whitetail buck bounce off and disappear over a ridgeline. Both hunters had spent the previous day's efforts in and out of warmed cabins, and I'm sure some condensation had formed inside the bolts of their rifles. (Winters here in Michigan can involve lots of snow. Living on a forested peninsula, we are subject to high humidity much of the year.) But condensation would not have been a problem had their bolts been properly cleaned.
Why is bolt cleaning so important? The manufacturer does not know how long a particular rifle will be on the shelf until you buy it. They also don't know how long it will be until you clean it. Rifles are shipped with their metal given a light coating of protective oil. Bolts are often covered with a light grease. After a few years in your warm, dry gun safe, a little bit of lint and some powder residue, the protective grease in your bolt can become a thick paste. Let the paste bind with some condensation, and when you walk out into a cold snap, the firing pin spring may not have enough force to weasel through the gunk and fire the chambered round.
The most common bolts you can clean are the Winchester Model 70 bolts, Springfield, Mauser and Remington Model 700s. If you have a Savage you should turn it over to a gunsmith. The Savage bolt must have the firing pin protrusion adjusted upon reassembly--a fussy job. Leave it to the pro. Tell him you want it cleaned to work in the cold. The other models you can scrub yourself. To do so, you'll need cleaning solvent, degreaser and a lubricating oil, a stiff-bristle brush, a section of cleaning rod and a plastic-bristle bore brush. Upon final reassembly you'll need a little dab of high-pressure grease.
Bolt disassembly of the Winchester, Springfield and Mauser are easy. Close the bolt on an empty chamber. Move the safety to the middle of the three positions and open and remove the bolt. Press the cocking piece locking button and unscrew the firing pin/cocking piece assembly. The Remington is a bit more involved, but not much. You do not need a bolt disassembly tool unless you are changing the spring or firing pin. For cleaning, you need a vise and a 1⁄8 drift punch. Remove the bolt from the rifle. Either hook the sear on the edge of your vise, or clamp it in the vise jaws. Pull on the bolt, compressing the firing pin spring. The firing pin extension will protrude further from the cocking piece, and you will see a cross hole through the extension. Push the drift punch through the hole and relax your pull on the bolt. You may now unscrew the bolt from the firing pin assembly.
Sporterized Mauser and Springfields with two-position safeties require the same method but, lacking the cross hole, you'll work with the assemblies uncocked.
Scrub the firing pin assembly with the stiff brush and bore solvent. You need a basic nitro solvent, and not a copper-removing one. There will be no copper in your bolt, only grease, oil and powder residue. I find that a basic solvent--Birchwood Casey or Shooters Choice--works great. Save the copper cleaners for the bore. Scour the firing pin spring and firing pin, working the bore solvent into the gaps of the springs coils. Once you have thoroughly scrubbed it, spray it down with degreaser, apply the bore solvent and scrub again. Those who want the graduate exercise can detail strip the firing pin assembly and scrub the spring while it is relaxed. The reason for the degreaser is to avoid further disassembly, but I shouldn't discourage those who wish to be thorough.
Degrease again, and spray or squirt your lubricant onto the spring and firing pin. I prefer synthetic lightweight lubricants for in-the-bolt application. I have had good luck with Break-Free and Shooters Choice FP-10. Both wick well onto the whole surface of the spring, and cling persistently until you use a degreaser to get them off at some future time.
Now comes the hard part. My customers had both gone this far, but when it came to cleaning the bolt they had simply squirted some oil into it, reassembled the bolt and went out to hunt. The grease left in the bolt body had been enough to foil their plans.
Cleaning the bolt can get messy, so spread some paper, or do the cleaning in a large sink. The plastic-bristle bore brush should be a 9mm/.38 handgun brush. Press a fingertip against the firing pin hole to prevent solvent from escaping, and pour bore solvent into the bolt body. With the bore brush on a single section of cleaning rod, scrub the bolt body thoroughly. If this is the first time the bolt has ever been cleaned out, you can now pour out some quite disgusting sludge. Pour in a bit more solvent and scrub again.
After scrubbing the second time, spray the degreaser into the bolt and let it dry. To lubricate the bolt, squirt a liberal amount of oil into the thread portion of the bolt body, and stand it on its breech face end on a dry piece of paper. When the oil comes out of the firing pin hole, turn the bolt over and stand it on the open end and leave it for about 10 minutes.
Once the oil that is going to run out has, reassemble. Wipe the firing pin assembly with a paper towel or oiled cloth. On the easy bolts, simply screw the assembly back into the bolt body until it clicks in place and stops. On Remington rifles, screw the bolt on until it stops. Back up slightly to align the sear with the full-cock notch. Pull the bolt, and remove the drift pin. On sporterized Mausers and Springfields, clamp the sear in a vise. Push the cocking piece forward with one hand while screwing the bolt body on with the other. Once you have a thread caught, you can pull on the bolt to cock it, and screw the bolt body on until it is fully in place.
Place that dab of high-pressure grease on the cocking cam of the bolt body. You'll find the bolt works a bit easier when greased. Don't worry about the grease setting in the cold and causing a problem. Your arm is stronger than the firing pin spring, and the grease will not keep you from working the bolt.