I’m pretty confident in saying more pages and social media ‘feeds’ regarding cleaning of firearms and what, when, why and how have been created than any other firearm maintenance topic. While shooters and hunters exist at opposite ends of the cleaning spectrum with many in between, it’s probably best I don’t try to re-invent the wheel, so to speak, but stick to what happens when we fire a bullet down the bore of a rifle and why cleaning your rifle bore is important.
Most barrels are made from chrome-moly steel or stainless steel using a number of processes which I won’t go into. The creation of a barrel and its bore will obviously leave tooling marks, with external marks being easily removed while internal marks can be dependant on the bore and chamber profiling process. Nevertheless custom-made barrels, which cost more, will tend to be hand-lapped to smooth out any such manufacturing imperfections prior to installing on a rifle, mass produced barrels probably not so.
Barrel ‘break-in’ is another hotly debated topic and there are many so-called experts out there all offering their two-cents worth. I only take the advice of a good friend who’s one of Australia’s leading gunsmiths and personally break-in all new barrels using a modified method which isn’t too time consuming. But if you don’t break-in a barrel it’s no big-deal, each to their own.
So to the matter in hand. When we fire a bullet (projectile) down a rifle bore we are in effect pushing a copper-covered slug through a bore using a propellant, generating heat which produces carbon. Copper from the bullet will slough on to the bore surface, including the grooves and lands, as well as the bore being coated in carbon and any other residue from burning of the propellant.
Thus, in Sara Lee analogy, ‘layer upon layer upon layer’ is what we get. Each layer, microscopically thin in dimension, is still fouling and impedes the progress of the next bullet and the next and so on. How many rounds does it take without removal of the fouling before accuracy tapers off? That I’ll leave to the individual and what each hunter and shooter wishes to achieve. Target and benchrest shooters are fairly fastidious in maintaining their gear in peak condition and will have detailed logs on how many rounds a particular barrel has seen. Hunters on the other hand may not clean a barrel for a year or more and this is perfectly acceptable as long as accuracy isn’t compromised.
However carbon, powder fouling and copper are the three items which will eventually need removing and knowing a bit about their chemical properties may assist in making your cleaning process a little less frustrating.
Carbon - one of the building blocks of all things animate and inanimate - is easily enough removed from a rifle bore using a hydrocarbon-based solvent, thus we use a solvent containing soluble carbon to remove the elemental carbon left over from burning of the propellant.
My initial rifle cleaning regimen is once I’ve passed a couple of dry, clean patches through the bore to remove loose or particulate fouling, I pass patches soaked with a suitable carbon solvent through the bore - in one direction - until most of the carbon fouling has subsided. You can let the carbon solvent sit a few minutes before passing the next patch and so on but this initial solvent application removes the most important barrel contaminant first-up.
Carbon-removing solvents are available specifically for firearms but many use automotive brake cleaning aerosols which perform the task well, though care must be taken to ensure exterior barrel and stock finishes are protected from exposure to cleaning solvents not tailored to firearms applications.
Copper in the form that bullets are furnished from is in the form of Cu+++ (the cuprous form). To remove Cu+++ from a rifle bore it must be chemically converted in some manner which basically involves converting it from its solid Cu+++ state to its Cu++ state (cupric form). Most copper solvents perform in this way and produce the tell-tale ‘copper-blue’ patches we’re used to seeing when cleaning rifle bores. However, some technically advanced solvents dissolve copper by chemically concerting the Cu+++ (cuprous) form to a soluble cuprous form without giving these copper-blue patches. These solvents very aggressively strip copper fouling from any rifle bore and can even dissolve copper fouling in ‘real-time’, hard to believe but true. There are a few copper solvents available which act in this way and which one you choose is totally up to yourself but, as always, personal protective equipment in the form of glasses, gloves and an old dustcoat or apron should be worn when using carbon and copper solvents for firearm maintenance.
Most brushes and jags for firearms maintenance are made from brass or phosphor-bronze, of which copper is a major constituent. Using any sort of copper solvent with a jag or brush that contains brass/bronze and you will get a ‘copper-blue’ colour on your patches when swabbing out your bore, widely referred to as a ‘false positive’. You may have a perfectly clean bore but when patch after patch come out ‘copper-blue’, that’s the copper solvent dissolving the jag or brush! To avoid any false positives, nickel-plated jags and nylon-brushes are available which don’t dissolve when exposed to copper solvents.
I use phosphor-bronze brushes when I need to remove recalcitrant copper and powder fouling and am fully aware the brush will be acted upon by the copper solvent. However, the phosphor-bronze brush does ‘scrub’ a tad harder than the nylon variety and is a better bet. As a tip, phosphor-bronze brushes can be cleaned and the effects of the copper solvent neutralized by washing them in shellite. I use a small bottle of shellite and can clearly see all the Cu++ fouling in the bottom of the bottle. The cleaned brushed can then be air dried and stored for next time.
For general cleaning I opt for nickel plated jags and nylon brushes with a nickel-plated core. The latter can be tricky to source but when I do find them I buy in bulk, opting for 6mm brushes to cover .243/6.5mm calibres and .30-calibre brushes to cover from 6.5mm up to .30 calibre rifles. Nickel-plated jags are easier to find and I use the Tipton brand. These brushes and jags eliminate any false positives, so if your patches come out clean (no blue or black) your bore is clean.
It’s not rocket science but knowing some of the ‘actual’ science behind what happens when you send a bullet down the rifle bore makes cleaning a little easier to understand.