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Introduction to the Lubrication of Firearms

There is endless debate and discussion when it comes to the lubrication of small arms. Every company has their own formula and everyone has a personal favorite. With all the hype and hearsay, it can be nearly impossible to separate fact from fiction. Hopefully, this explanation will provide some insight.

I will attempt to avoid the use of the term ‘gun oil’ as there are many dry lubes on the market. However, this should not be taken to mean that gun oil (or any other oil) is excluded from this discussion.

I would also like to point out that I am intentionally ignoring the question of running a firearm completely 'dry' - meaning completely unlubricated. One may be able to argue for a dry lube, but not using any lubricant at all is simply not a good idea.

The bottom line is this—a firearm is a machine. It is a mechanical device with moving parts that performs a function. The primary purpose of lubricant in a machine is to reduce friction between moving parts and thereby improve function and reduce wear. 

At first glance, this realization would appear to make the choice easy, simply find the product that reduces friction the most and you are set. However, as we all know, the truth is much more complicated. While the primary purpose of a lubricant may be to reduce friction that is not the only purpose of gun lubricant. Aside from reducing friction, gun lubricant also provides protection from corrosion and keeps contaminants in suspension to simplify cleaning. So now there are at least three functions; cleaning, lubricating and protecting. Hence the military uses the term CLP rather 'gun lubricants' or 'gun oils.'

The first issue is that not all lubricants are equally effective on all materials or conditions. The best lubricant for a polymer to carbon steel interface is not the necessarily the best lubricant for stainless steel to carbon steel interface. Also, the effectiveness of lubricants varies with the pressure on the bearing surface. This why there are so many different ‘weights’ of automotive oils. 

To make things even more complicated, firearms have to work in a wide range of environments. Temperatures can range from artic to desert conditions. The environment can be wet or dry. The operational area can be clean or dirty. And if that isn’t enough, there are issues such as salt or other corrosives in the environment. Even the size, shape, and consistency of dirt particles in the environment will greatly affect the operation of a firearm.

There is no single lubricant that is best at all jobs in all environments. The following paragraphs will attempt to give a short introduction to the impact of environmental factors.

Temperature is the first item to consider. Liquid lubricants will vary in viscosity (thickness) with temperature. The lower the temperature, the thicker the lubricant will be. This means that any liquid lubricant must have a temperature range that allows it to function as intended regardless of the environment it is used in. This includes considering how the lubricant will function when the firearm’s temperature is increases as a result of heavy use.

The next environmental factor to consider is the presence of water. Water can adversely affect the function of many lubricants. Lubricants such as dry graphite are fairly easily displaced by heavy contact with water.

Now comes the point of real debate: lubricants in dusty or dirty environments. There is a lot of discussion around wet lubricants and sandy environments. The concern is that the wet lubricant will attract sand and grit thereby preventing the weapon from functioning. 

To really look at this issue of wet lubricants and sand/grit we need to consider a few points. The first is a rough understanding how grit ‘sticks’ to a liquid lubricant. The very short version is that the thicker the liquid, the larger the particle it will hold. The problem is that almost any lubricating oil is thick enough to pick up grit that is large enough to interfere with the weapon.

So, if lubricating oil can pick up grit why not use a completely dry lube? Well, there are some pros and cons: Dry lubes work very well in clean environments, but not as well in very gritty environments. The reason for this is that dry lubricants tend to form very thin films, as the excess simply falls away. This means that while effective at reducing the friction between the moving parts they are not as effective at coating and lubricating the grit that finds its way into the firearm.

Anyone who has worked around sand will tell you that no matter what you do to prevent it, some sand will work its way into your firearm. So this leaves the million dollar question: Is it better to have a dry-lubed weapon that will hold less girt or a liquid lubed weapon that will more effectively lubricate the grit that is there?  

The issue is how much grit gets into the firearm versus how much grit falls back out of the firearm. Using a using a wet or dry lube has little impact on how much grit gets into a weapon, but is does affect how much falls back out. If a weapon is dropped in the sand the same amount of sand is in contact with the weapon regardless of how it is lubricated. The question is how much sand will remain in contact with the weapons moving parts once you pick it back up. The key here is moving parts. We don’t care how much sand is stuck to the outside of the stock; we only care about how much grit is in the mechanical works of the weapon.

Imagine you have two identical firearms and both are disassembled. One is dry lubricated and other is wet lubricated, and then the parts from both are rolled around in a barrel of sand and reassembled. If you asked me which on I would prefer take to battle, I would pick the one with a dry lubricant. A wet lube would simply pick up too much grit in such a circumstance. However, if I had to pick between firearms that were cleaned, lubed, and then simply buried in the sand intact, I would likely pick the one with the wet lubricant because a wet lube is more likely to be able to overcome a moderate amount of grit.

This is one of those topics that develops firm believers on both sides. The debate is fueled by the fact that all weapons will suffer more failures in a sandy/gritty environment regardless of what lubricant is used. Sand simply isn’t good for weapons and those operating in sandy environments need plan for a higher failure rate in equipment.

A more in depth discussion of wet versus dry lubricants will be the subject of a future article.

The next environmental consideration is the corrosiveness of the environment. The first issue that arises when talking about protection from corrosive environments is the recognition that not all materials are equally vulnerable. For instance, salt water may corrode carbon steel quickly, but barely affect stainless steel. Also, there are many types of stainless steels and some are more corrosion resistant than others. This means that depending on what the firearm is made of, the need for protection varies. Most military firearms still contain quite a bit of carbon steel and so require protection from the environment.

Another consideration when it comes to protection from corrosion is the corrosiveness of the lubricant itself. Some lubricants, such as graphite and molybdenum disulfide can accelerate corrosion. Graphite can cause a galvanic reaction with some materials and molybdenum disulfide can form acidic compounds. In both cases, the effect is made more severe by contact with water. This is not to say that neither of these products should ever be used, but one needs to understand the pros and cons.

The last item to evaluate is the cleaning aspect of gun oils and lubricants. This is not meant to suggest that you should only use one product for both cleaning and lubricating firearms. Attempting to remove copper fouling with the same product you use to lubricate is generally only marginally effective. However, in the field sometimes you have to make do. Also, the lubricant you use on your firearm will greatly affect how easy it is to clean. A coating of lubricant on a firearm acts much the same way as a coating of oil or butter does in a pan. It provides a barrier that prevents things from sticking to the underlying metal. 

The take home lessons from all of this are:

1.) A dirty unlubed gun probably won't run, but a dirty lubed gun probably will, so use a lubricant.

2.) A clean gun will nearly always run, so clean often.