Rifle cleaning

Gun cleaning: dealing with carbon build-up in the barrel

The presence of carbon in rifle barrels is nothing new; man has been dealing with the problem for a long time. For many years we have used cleaning liquids that supposedly attacked copper and carbon residue, or so we are told. 

In my case, the initial patches I put down the barrel were wet with either brake cleaner or carburettor cleaner. They removed most of the loose combustion residue. 

All copper-jacket projectiles will leave copper in the bore, some more than others!

About a year ago I decided that perhaps some of the newer brushless liquids might be worth looking at. A shooting mate suggested Bore Tech Eliminator. 

At this stage, I did a lot of further research about carbon in rifle bores, concluding that there are three distinct types of carbon that occur in a rifle barrel.


The first type might be termed loose carbon and occurs the length of the barrel as a result of normal combustion of powder and, to a much lesser extent, the primer. 

This type of residue/carbon is easily removed by the initial wet patch down the barrel during the cleaning process. 

Bore cleaning patch
Visible evidence of hard carbon within the bore


The second type of carbon seems to mix with the copper from the projectile and is layered onto the barrel by the next projectile down the bore. 

This mixture appears to be the focus of most cleaning liquids that are designed to attack both the copper and carbon residue, either with or without the use of a bronze brush.

The brush literally etches the copper and, besides a scrubbing action, allows a greater surface area for the liquid to work on both the copper and carbon. 

The latest liquids do not require a brush; they are patched out after a suitable time interval. 

Despite using both methods and various liquids, I was still getting black streaks of carbon after many patches. 

Dedicated bore pastes will remove the hard carbon


The third type of carbon is obviously a function of great heat and pressure. It is literally plated onto the barrel just forward of the chamber. It is, of course, the most difficult to remove. 

Many years ago, a retired metallurgist told me that there was no solvent known to have any effect on carbon.

Carbon will, over time, very slowly build up just forward of the throat due to intense temperature and pressure. Only the correct use of an abrasive or a bronze brush, or a combination of the two, will eliminate it from the bore. 

In addition, the type of barrel steel and speed of firing must be considered; it is a fact that allowing a barrel to get hot is detrimental to barrel life and must be avoided at all costs. 

But the question remains, is there any fluid that will completely prevent carbon build-up in a bore? 

Probably not. This third type of carbon build-up is, I suggest, extremely hard and it is obvious that normal bore-cleaning fluids are incapable of penetrating the layer. 

My research leads to the conclusion that only abrasive paste will work. Barrel maker Lilja suggests a scrub every 700 rounds or so.




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Ron James