Firearm Maintenance and Precautions for Cold Weather
Winter weather presents its own unique challenges for the shooter. As the mercury dives below zero, actions can seize, powders and primers cease to operate effectively and wood can splinter. Military forces around the world have known this since before the first modern rifles were even conceived, where wind and ice swung the tide of war for such luminaries as Napoleon, Peter the Great and George Washington. Before the advent of the percussion cap, alpine and arctic campaigns routinely experienced misfire rates over 30 percent due to the effects of cold. Doughboys in Chosin during the Korean Conflict not only fought Korean and Chinese onslaughts, but also the almost constant malfunctions of machine guns, rifles and their beloved 1911's as temperatures dipped below freezing. Even today in places like Alaska, Canada, Russia and Scandinavia, soldiers and hunters alike must take special precautions to prevent stoppages caused by the frigid northern reaches. However, some very simple steps can help ensure that Old Man Winter's icy touch doesn't put a short end to next excursion.
Lubricants are designed to reduce the wear of parts moving against each other and the heat generated by the friction of that movement. In normal conditions, the viscosity of lubricants creates a protective layer between the moving parts of a firearm's action in the same way as in a car's engine. Natural and synthetic lubricants are designed to resist extreme amounts of heat so as to not break down through the fast, repetitive cycling of modern firearms, especially automatic ones. Yet few are capable of retaining their viscosity when exposed to sub-zero temperatures. In the freezing weather, lubricants begin to bind and set, becoming gummy. As the mercury continues to fall, some lubricants can even begin to freeze, rendering them almost as hard as epoxy. In fact, one of the only gun lubricants currently available for extreme cold conditions is a blended vegetable and synthetic based, biodegradable product from United Bio Lube called "Bio Arctic," which has been tested by the army to function at temperatures below -50 Fahrenheit. Unfortunately, at the time of this writing, "Bio Arctic" is only available wholesale to gun manufacturers and for government procurement, leaving the majority of shooters "in the cold."
For the majority, there is only one reasonable solution. This is simply to clean the action of all fluids and lubricants. There is little risk of damage from friction, as the extreme temperatures will moderate heat within the firearm. Also, the amount of wear incurred by the lack of lubrication over shorter time spans is generally negligible, and easily managed by action smoothing by a qualified gunsmith. The important thing to remember here is that every trace of lubricant and the cleaner used to remove it must be completely gone before the weapon is exposed to the environment.
But lubricants are not the only liquid in a gun's action. Air contains moisture. As that air is cooled, it can no longer hold moisture and so it collects on surfaces. Think of the way condensation collects on the side of a water glass. The same thing happens to a cold rifle brought into a warm room. Moisture will begin almost immediately on every surface of the rifle, inside and out. By itself, this is not inherently bad. The risk comes as that now damp rifle is brought back out into the cold. The condensation will begin very quickly to freeze on all those surfaces. This can cause the weapon to lock, not firing, or to fire, creating high stress on the internal structures. In gas or short throw piston operated repeaters such as AR-15 type rifles, a frozen action can cause excessive back-pressure in the gas tube which can permanently damage the gas block. Scandinavian special forces for years have had to contend with back-pressure during arctic conditions causing the selectable gas blocks on their M-4 type rifles to jump positions.
The solution is to make a habit of cleaning all firearms when coming in from the cold. By stripping down and drying off all the components, there will be little or no moisture to freeze in the barrel or action when the weapon is brought back out into the cold weather. An important part of this process is to inspect each and every cartridge of ammunition to ensure that ice has not damaged cases, crimpings or primers. Any suspicious rounds should be properly discarded and replaced. A few minutes spent cleaning can mean the difference between click and bang.
With the cold often comes sleet and snow. Winter precipitation can spoil a good shot just as quickly as a bad twitch. Snow and ice can collect in a barrel and action just as water does, but pose the additional problem of then freezing as they settle on the cold metal. Some hunters routinely carry their slung rifles muzzle down when traversing terrain in foul weather, but this does not protect parts such as bolts and triggers. Optimally, the answer is a sleeve or scabbard that can be sealed against the elements. Although not always practical for the extra weight, bulk and time necessary to make ready for a shot, a sleeve does offer the best barrier. Muzzle caps are another option, but just as carrying muzzle down, they will not protect the action. For the action, if a sleeve is not an option, the best alternative is plain old, everyday plastic wrap from the kitchen cupboard. it is easily removed to set up for a shot, and conforms to the contours of the weapon without adding unwanted weight or bulk. The key to plastic wrap is to keep it off the ground when not being used. Placing it in a pocket when its not on the rifle will prevent it from resting on something wet or snowy before going back on the gun. When used with a muzzle cap, this offers a descent amount of protection from winter precipitation.
Perhaps the greatest risk to the winter shooter is that of the cold effects on the metal itself. Rifle barrels are tempered to increase strength and resist warping under high heat and pressures. But when tempered metal is exposed to sub-zero temperatures it can become brittle. Rapid increases in heat and pressure under these conditions can stress the metal and create abnormally fast wear, or even small stress fractures. Typically, this is only an issue for automatic weapons, however rapid cycling of any firearm should not be attempted until a few rounds have been put down range at a moderated rate of fire to allow the barrel and action to warm up more slowly.
Two items of special mention are firing pins and cartridge case materials. Some cartridge cases are clad in nickel. Originally, this was done for the corrosion resistance of nickel as compared with steel or brass. When carried exposed in a gun belt or bandolier, nickel plated cases showed less patina and oxidation over time. It has been suggested time and again that the higher lubricity of nickel allows for better feeding in arctic conditions where micro-crystals of ice may accumulate on surfaces. While at face value, this seems reasonable and the logic is basically sound, there has yet to be a scientific study done to test such if such an advantage actually exists. Likewise, much has been said over the years regarding the use of an increased firing pin fall in sub-zero temperatures. Most primers today use some proprietary mixture of shock sensitive low-level explosive material such as lead styphnate, lead azide, potassium perchlorate or diazodinitrophenol. These chemicals convert impact force or a static electric charge into an exothermic reaction that ignites the main charge in the cartridge. In extreme cold, primers and powders may react more slowly, possibly causing a hang fire. The suggestion is that a harder impact will ensure an efficient detonation of the primer in colder temperatures. Since to date, there has only been allegorical evidence of cold induced hang fire with modern rifle or magnum Boxer primers, and taking into account both the amount of heat generated at a specific rate by the reaction and the velocity of detonation which takes place, it is unlikely that a greater than normal firing pin fall is necessary in any but the most extreme environments.
The cold does, however, effect the external ballistics of a fired round. Cold air is more dense than warm air, creating more resistance to a bullet passing through it, and more force pushing the bullet off course in a crosswind. For example, air at 77 degrees Fahrenheit has a density of 1.183 ounces per cubic foot, while air at 32 degrees Fahrenheit has a density of 1.291 ounces per cubic foot and air at 13 degrees below zero has a density of 1.421 ounces per cubic foot. That's roughly 1 percent for every 4.5 degrees. British artillery regiments fighting in the mountains of Central Asia during World War II studied the effects of the sub-zero temperatures on their guns' range and accuracy. Understanding the difference in air density at different temperatures and elevations, they quantified a 2:3 ratio of temperature to range reduction. In other words, for every 2 degrees (Celsius) below freezing, approximately 3.6 degrees Fahrenheit, they would calculate a 3 percent loss of effective reach. If that doesn't sound significant, consider that a drop in temperature from 32 to 0 degrees Fahrenheit can knock up to 400 yards off the effective range of a .308 Winchester round.
Finally, the shooter should remain cognizant of the smaller details. Bulkier clothing worn during winter can place a rifle farther forward than normal, in effect extending the length of pull slightly. This can also put the eyepiece of a scope further from the shooter's head. Repositioning a scope and re-zeroing a rifle may be prudent precautions for maintaining accuracy. Gloves may may a trigger pull seem longer as the insulating fibers compress under pressure before the trigger actually moves. Of course, in sub-zero weather, the metal of any firearm should never be touched with bare skin. Frostbite through contact with cold metal can happen within seconds.
In the end, cold winds and snow are not insurmountable. While harsh environments can offer different ways to mechanically stymie the shooter, frozen weather need not be a deterrent to a fun day afield. So long as a few simple precautions are taken and a little extra maintenance performed, even the coldest temperatures will not take away from finding that perfect shot.
Copyright 2011 by Adam S. Gubar and/or chuckhawks.com. All rights reserved.