Smarter Barrel Cleaning

Maintained is better than clean.

There are multiple approaches to cleaning and barrel break-in. This video presents one approach.

This article has other opinions.

I have been a barrel maker a fair amount of time and my barrels have set and reset benchrest world records so many times I quit keeping track (at one time they held seven records simultaneously) along with High Power, Silhouette, and Smallbore national and world records. I inspect every barrel taken off and every new barrel before it is shipped with a bore scope and I will tell you all that I see far more barrels ruined by cleaning rods than I see worn out from normal wear and tear.

- Gale McMillan

Ideally, use a cleaning rod guide in the receiver that has a rod-specific bushing. Keep the rod centered and in line with the bore!

Several rifle barrel cleaning and break-in procedures have been described over the years. Detailed inspections of many barrels with quality borescopes lead to improved conclusions about the impact of various cleaning and break-in procedures.

With borescope inspection, it became apparent that the bore condition of match-quality barrels varied widely from barrel to barrel. Some barrels indicated little to no cracks and abrasion while others showed severe cracks and abrasion in the neck and throat. Some of the barrels even showed gross pitting the length of the barrel. One could quickly assume that the varying levels of fire cracking have a direct correlation with the number of rounds fired through the barrels. However, documentation of the actual number of rounds fired through many of the barrels revealed that the number of rounds did not predict the fire cracking that was observed. Some barrels with less than 100 rounds showed fire cracking while others with 3,500-plus rounds through them showed little.

Follow-up on the life history of the barrels with the most severe fire cracking showed that they had been conditioned with a one-shot-and-clean break-in procedure with strong ammonia-based cleaners for the first 20 to 50 rounds or had strong ammonia-based cleaners used routinely through the life of the barrels.

The best-appearing barrels had a history of little or no abrasive or strong ammonia-based cleaners used in them.

It is uncertain at this time what mechanism is in place to cause the severe and/or advanced states of what appears to be fire cracking in barrels cleaned routinely with ammonia-based cleaners. One hypothesis is that it is a combination of a lack of lubrication and some form of sensitization and/or corrosion. Barrel cleaners that utilize ammonia are very effective at removing copper, yet at the same time, they are extremely volatile and leave metal surfaces very dry. The dry surface when contacted by a bullet that is also dry most likely is more prone to scratching, galling, and deformation than a lubricated surface. The resultant scratches and cracks then may or may not provide conditions for chemical attack and stress cracking.

Barrels cleaned exclusively with a mild solvent (Shooter's Choice or Hoppe’s No. 9 are examples) show little or no evidence of copper wash or fouling after extensive firing. Also, these barrels don't normally show evidence of fire cracking even with 3,500-plus rounds through them. Shooter's Choice tends to leave a lubricated bore even when multiple dry patches are run through the bore.

Shooters should review and assess techniques for cleaning and break-in. Part of this assessment is to consider that a barrel break-in is not necessary at all. For example, many successful national champion rifle competitors have stated their “break-in” is nothing more than establishing initial zeros prior to confirming at a local match with only their typical, minimal cleaning after each firing session. While not a universal view, at least one barrel maker has commented that break-in procedures are a scam perpetrated by other makers as a means to accelerate wear on new barrels to spur repeat sales. Other barrel makers have noted that even with detailed borescope inspections of fired barrels it is impossible to tell if a barrel was “properly” broken in or not.

The objectives of cleaning and break-in need to be understood and evaluated to determine whether they provide improved accuracy and precision in the rifle. Are green or green-tinted patches bad when the rifle continues to perform? Is a metal bore brush necessary when a nylon brush or just a few patches will do? Does our cleaning method add to the propensity of the barrel to foul, thereby requiring further cleaning efforts? Does slick and really clean make things better or is it damaging the throat and precise dimensions and surface texture that were the result of a very precise and careful manufacturing process?

Based on these observations, less aggressive cleaning approaches are generally favored. Ammunition since the 1940s does not require cleaning after every range session. When cleaning is called for, a milder solvent should be preferred as well as less abrasive cleaning products and tools.