How much copper is too much?

[Muddly]

My 111 Savage .270 Winchester picks up her fair share of copper. Removal of the powder fouling shows color from land to land. It just seems to be color though. No lumps or streaking, it seems like what the Barnes manual refers to as "coloring". I use Hornady and Sierra bullets at various velocities and full or modest loads leave the same amount. Its not difficult to remove with Sweets 7.62. Accuracy doesnt seem terribly effected by it, BUT, a clean copper free bore throws a flyer for the first shot. So how much is too much? Wait till accuracy goes or the lumps/streaks appear and do you remove it all or leave abit? Most of my centerfire experience is with 30-30 class rounds which didn't leave much copper in my rifles. Any thoughts appreciated!

[gunnut69]

Most rifles shot best slightly fouled  but metal fouling can holed moisture next to the steel of the bore creating rust and eventually pits..  I hunt with rifles fouled from sight in shots but clean extremely well for long term storage..

[keith44]

My competitive shooting friends will shoot one match then clean all fouling from their bores.  The next day they shoot the next heat and clean that night.


So to answer the question of how much copper fouling is too much, it depends.  1,200 yards into a 6 inch group, no fouling at all is permitted.  500 yards into a 6 inch group, what ever sight in fouling is in the bore can be left through the hunting season, but like gunnut69 said should be removed prior to putting the gun up until the next season.  3"groups at 150 to 300 yards is the bottom rung of precision shooting with "big guns"and metal fouling can almost be ignored.  A good penetrating oil will lift out any fouling that will allow moisture build up.  A stiff brush followed by a patch is enough.