I have just cleaned the bore of my Ruger m77/II 300 Win. M. cal. with good quality solvents. While passing brush and patches, I felt some roughness in the first 2 inches +/- ahead of chamber. I tried repeatedly with JB compound, but the roughness resists. I have shot 700/800 rounds, never used very slow burning powders, and I always wait 1 or 2 minutes between the shots. Any idea? Thanks - Lorenzo

It's heavy fouling. A shot out throat won't feel rough like that...

I had a .243 which had a similar problem. You could feel the rough spot when you ran a patched jag down the bore.

I don't believe the JB is abrasive enough to handle the problem--at least not without a helluva lot of polishing.

I ended up firelapping the afformentioned .243 barrel, and it's better than ever before now. You may want to check into a firelapping kit like Wheeler's, or just order the Tubb's Final Finish kit. Firelapping is well worth the effort if it is done correctly.

The problem I had with that .243 is I had moly over copper over moly over copper... Have you been shooting both moly and copper bullets through this rifle? That may be the problem...

There may be some solvents that will effectively attack that mess, but I'm not aware of which ones to recommend.

The firelapping will solve the problem entirely.

Failing that, you could use a bronze brush with some Butch's or Shooter's Choice and work it to and fro, just over the heavily fouled area. This would work best after the barrel had been heated up by firing a few rounds down range, then go right to scrubbing.

Let us know how things go...

Dan Newberry
green 788

JB works better in a warm barrel too, but it sounds like bad copper fouling to me and in that regard I've found that a combination of JB and Sweets will get the job done. Get the powder residue out then plug the bore and fill it with Sweets for about 10-15 minutes. Drain, swab and try some more JB. Repeat as needed. The first go round with the Sweets should result in a fairly deep blue color when drained. If not, it's not copper fouling. If you spend a lot of time with Sweets or other high ammonia content solvents on a copper brush your brush will go bye bye. It will also color the solvent blue/green and you'll think the bore is still fouled. Best use a nylon brush if you want to brush...I don't.

My 6.5x55 suffers from this. Even after one shot the first 4 inches or so of barrel feel rough.

It seems to be mostly fouling but that might be caused by some underlying roughness of the bore.

A few scrubs with a good bronze brush removes it.