Jurome,
I have used various bore cleaners and copper cleaners including Hoppe's, Sweet's 7.62, Kroil oil & J-B bore cleaning compound, Butch's Bore Shine, and Wipe-out.
In my opinion, the easiest and best way to remove copper is with Wipe-Out. Use a 3/16 hose to foam it into the chamber end...
Chuck,
I have shot both JD338's 35 Whelen and my own 375 Ruger. In my opinion, the recoil on the 375 Ruger is much more than that of 35 Whelen. In fact, I shot my 375 Ruger just 7 times. I found shooting the 375 Ruger to be very unpleasant, and I immediately swapped it off for a BLR chambered...