I've just inherited a Steyr-Mannlicher model L, probably mid 1970s vintage.
It is a lovely gun, and the previous owner took meticulous care of the outside. But doesn't seem to have done anything witht he bore. Doing a little detective work, the last time the bore was cleaned was at least 6 years ago, and it was shot fairly regularly during that time (first swab of the action even came out with pine needles).
On initial inspection, there was a very visible build up of fouling and rust in the bore. I've spent 2 evenings alternating a bronze brush and Wipeout. The patches are still coming out black, though there has been a reduction in visible crud in the barrel by about half.
I'd be very grateful if people could suggest where to go next with the cleaning.