Thanks Stan and Skeet. It's a venture, a journey into the unknown trying to help an unknown with so many variables, all out of your control. Thank you. For a rebarreled Mauser, it shoots very well. 0.5 to 0.65 best so far at 100, with three in one large hole, and under just 2 1/2" at 300. That's 142gr SMK @ 2,8000 fps. Not really that hot. This is Benchrest central, and I am not a benchrest competitor. But this is a priceless source of information and knowledge. I have used J&B once about 7 weeks ago. I was using Hoppes 7 and 9. Not any more as compared to the Shooters Choice I am now using they seem to be very weak. i.e I can patch, nylon bore brush, and patch with the Hoppes until no more dark (powder) or blue/green can be removed. Then go back in with the Shooters choice and get 5-10 more discolored patches out. I have used two, 5-7 minute wet patch soak SC copper remover. I haven't let that mixture set more than 7 minutes, trust me, as I am aware that it has ammonia in it. Case in point, I cleaned over the last 4 days with three, 8-10 hour SC wet patch soaks, until no more fouling came out. Ran one wet patch SC last night and this AM there is some green on the patch. Can't get a decent macro photo, sorry. I use a bore guide, and with the exception of the J&B, I always push the patch to the end, then walk around and remove the patch, then very carefully draw the rod back through the receiver. Unless the SMK 142s are made of marshmallow gilding metal, I have a fouling problem. I didn't know any better until I was talking to people that shoot the lapped custom stainless in .308 and they all agree that they clean real easy, simple, no problemo. I am going to pick up some Wipe Out and a bore plug to finish this little fellah off, then start fresh and see what happens......
Edit: I bought this barrel new from Brownells in 1997. It was professionally installed, chambered in then a wildcat 6.5-06. Other than cleaning it shoots very well out of a 27-inch 6.5 cal barrel, 99-yo action from the original wood military stock.