BARRELS: BREAK-IN AND CLEANING

Maintenance and cleaning often spark debate, with even rifle manufacturers avoiding firm recommendations. But for us at Hexagon Ammunition, performance is everything. We’ve spent a lot of time testing practices to eliminate unhelpful habits, ensuring our customers get the best velocity, precision, and value from our products, writes Paul Bradley, Hexagon Ammunition.

BARREL BREAK-IN

When you pay a lot of money for a new rifle, you want to ensure you look after it. This often starts with the concept of barrel break-in. The procedures range from the simple to the lengthy and complex. A complex break-in procedure can take a day or more and involves a series of bore cleans, both abrasive and chemical, interspersed with rounds fired. I have heard all manner of variations, but it is usually something like copper-brushing the bore, running several cleaning patches through with a solvent or CLP, shooting a round, and repeating brushing and patching. The repetition can go on for many rounds, and some have suggested leaving solvents to work overnight or even for 24 hours. To understand the best procedure, let’s first consider what we are trying to achieve.

A rifle barrel is made of steel and may be chrome-lined. Firstly, we should bear in mind that in most countries, the barrel will already have had shots through it as part of the proofing requirement. The proof house does not conduct any break-in procedure. So the idea that you need to do anything before a bullet passes through the bore has already been decided for you. The only feasible reason you would want to conduct a “break-in” procedure is due to swarf or debris in the bore or imperfections.

Let’s address imperfections first. You cannot clean or brush away imperfections. All barrels are imperfect to a degree; there is no such thing as a perfectly smooth surface. If you view it with enough magnification, you will see imperfections. It boils down to how much imperfection is acceptable in your system. Hopefully, the manufacturer has a good enough quality procedure to weed out barrels that do not make the cut. The removal of swarf or foreign debris is a sensible idea as it pertains to both performance and safety. Simply passing a copper brush followed by a CLP-treated patch will be enough to remove such items. No need to keep repeating that multiple times.

In terms of firing rounds down a new barrel, we do have a procedure, but it has little to do with break-in and everything to do with quality assessment. I carefully shoot three- or five-shot groups with the new barrel, letting the barrel cool in between each group. This is no different to my standard procedure when assessing the precision of a system (or part of it). I expect to see precision improve after around 20 rounds. This is because the projectiles leave part of their material in the bore. You are lining the bore with a thin coating of copper. The softer copper fills any small imperfections, creating ideal conditions for the projectile to travel through. In essence, it creates a snug fit for the projectile and a consistent level of friction during its travel. We should see velocities and our groups tighten slightly. I would try a variety of different projectile weights and charge weights during this period to ascertain which suits the rifle. To me, this is not a “break-in” – it is just load testing with a new rifle. It should be conducted methodically and carefully, as should any load testing, to minimise errors.

BORE CLEANING

If we have established that our bore reaches peak performance after lining with projectile material, we must also accept that cleaning it back to its original condition every time we shoot may not make much sense. Such a cleaning regimen remains popular and, in my opinion, is born partly from best intentions and partly as a historical hangover. Not so long ago, the energetic materials used in ammunition were incredibly corrosive. A person would clean their firearm after every use or likely find it badly pitted from chemical erosion. Thankfully, both propellant and primer technology have moved on considerably. Modern iterations no longer corrode your bore.

I have heard it argued that the military clean their firearms after every use, and people view that as a blueprint for their own regimen. The military have a slightly different way of doing things, some of which is about discipline and consistent behaviours that can be easily monitored. If infantrymen were instructed to clean their rifles only when they deemed it necessary, some would neglect to do it at all. Cleaning after every use is certainly better than never.

A rifle will plateau in terms of precision performance for a number of rounds between cleaning sessions. It differs by calibre and rifle but, in general, it can range from 100 to 500-plus rounds. There comes a point when copper and carbon deposits accumulate too much, and precision begins to suffer. Experience will teach you when this occurs. At this point, I would administer a full clean using both carbon-and copper-removing chemicals and an abrasive such as a copper or brass brush. The bore would be returned to its original condition (apart from any wear), and the process of lining the bore with projectile material to increase accuracy would begin again.

Now, I would caveat the above procedure. If the rifle has been used in an environment that introduces water, salt, or grit, we must account for that. A damp or wet firearm should be dried and lightly oiled; salt or grit must be removed. It is not necessary to remove copper from the bore every time one conducts basic environmental cleaning. A bore can be patched dry and again with oil without a complete carbon and copper removal. You may even extend the bore life with such a practice, as the coating within the bore will provide some level of protection to the steel beneath. You will certainly extend barrel life by shooting fewer rounds through it, and the above negates the need for “barrel warmers” or rounds to line the bore every time you go back out. This regimen also ensures you keep your POI as consistent as possible. Changes in POI from the first few shots are often blamed on the “cold bore” – hence the name “cold bore shot”. In fact, much of the POI shift may simply be down to relining your bore with projectile material.

As with all things firearm-related, the above requires a great deal of responsibility. It should never be an excuse to do less work. Paying close attention to your rifle and having some mechanical sympathy are vital elements. If you notice a firearm performing differently in any way, you should be able to understand why. If you cannot understand the change, stop shooting and investigate. If in doubt regarding cleaning, always opt to clean. It just means you will burn a few rounds getting back to peak performance – not the end of the world. Failure to clean can lead to far worse outcomes, such as a blown barrel or personal injury.