I hunted in South Dakota last week and the tribal guide for my daughter and her extended family is a long time friend of mine who is a real gunner but lives so far out in the sticks that a trip to the gun store to indulge his likes is a a 180 mile drive. I remembered that he liked Swedish Mausers so I dug into my lot of Swedes and found a decent M-1896 to bring to him dated 1918. In the process of looking I got to inspecting the bores on all of them. Many of these were purchased in a LOT of 10 rifles lashed to a shipping pallet and I'd never really inspected them. One rifle in particular had a very blackened, rough-looking bore but was otherwise a pristine 1920 dated Carl Gustav so I set aside to be rebarreled with one of the new, in-the-white CG barrels I'd bought in the 1980's.
In the shop I was cleaning the rifle I'd bring to my friend and decided to push a patch through the 1920 to see how bad it was. Well! Out came a plug of grease! Two more Hoppes-soaked patches and the bore was brilliantly bright with deep, sharp rifling. Gad! That was a nice surprise!~Muir