I don't often mention it on this forum, because my beloved 303 British from SSK is 26" long, but here goes. I really love to shoot this barrel and caliber. I bought my first deer rifle at a gun show in town when I was in high school; it was a No5, Mk 1 Enfield, the jungle carbine. I hunted with that rifle and it became a trusted woods companion. Naturally, when I went the Encore route, I had SSK make me a barrel for my favorite (at the time) cartridge. The barrel is a 26" with a slight taper. It shoots great out to my self-implosed limit of 300 yards and I've shot it allot.
Now for the question. I've had the barrel for four years and fired probably 300 rounds through it and it still gets a large amount of copper build-up in the barrel. I know I'm well beyond the break-in period and I did follow JD's break-in procedure when I first got the barrel. No matter what bullet I shoot, no matter how well I clean it, it still gets copper build-up within the first 10 shots and it gets progessively worse the more I shoot it, between cleanings. Before I started handloading, I bought 25 boxes of the Federal High Energy 180gr Trophy Bonded Bear Claw ammo that they produced a while back at a steeply discounted price and have shot nothing but these in it for about the last 8-9 months and it gets copper and more copper.
Anything I can do, or do I have to live with this barrel and it's copper build-up problem? It's worth living with as I like the cartridge, but surely I can do something to help.