by jshuberg on Sat Feb 15, 2014 9:08 am
For copper fouling there's nothing that works better than KG-12. Normally I'm not a fan of removing copper fouling until it becomes a problem, but my machine gun gets caked up with copper every time I take her out. A boresnake through the barrel 10X when still warm, half a dozen patches with Hoppes, and then 2 patches with KG-12 and the bore is absolutely spotless. Make sure to use nylon brushes and jags when using any copper solvent, it will attack bronze as it is mainly copper.
While Hoppes and other carbon solvents don't remove copper fouling, they can act as a copper indicator. After cleaning the carbon fouling out of the bore, run a wet patch through and leave it for around 5 mins. Then run a dry patch through. If it comes out with a lot of green or blue, it's indication of copper fouling. It's usually not a big deal, and actually tightens up the barrel, but excessive copper fouling will cause a loss of accuracy, especially if it gets to the crown. After removing copper it usually takes 25-50 fouling rounds to season the bore and get your accuracy back.
Most people over clean their barrels. Copper and even some carbon fouling is fine as long as it's not excessive, and fouling can actually protect the surface of the bore. The first few microns of the steel undergo metallurgical changes when the weapon is fired as carbon is introduced into the steel at extremely high pressures and temperatures, making it incredibly brittle. Every time you clean the bore you are removing a microscopic amount of the surface, but when you shoot the rifle, the hard layer of fouling actually helps to protect the brittle layer against the friction of the bullets. Shooting a rifle is easier on the bore than cleaning it. Everything other than the bore should be cleaned to spotless every time you shoot it, but be cautious and gentle with the bore. It just needs to be clean enough to shoot properly.
One simple trick to extend the life of your cleaning brushes is after your done using them, dunk them in a jar of isopropyl alcohol and stir them around for 20 seconds or so to remove all of the solvent from the brush. Over time, those solvents will eat away at the bristles and spindle of the brush, causing the bristles to fall out. I've found you can almost double the usable life of a cleaning brush by cleaning them thoroughly after use.
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