Leaving everything else aside, all you need to know is that at some point, shooting cast bullets only, you'll get leading, and lots of it. There's no attainable speed that will do damage to the barrel from speed alone, unless you want to stipulate that damage due to aggressive de-leading methods counts.
Shooting metal patch bullets, there's no speed slow enough to eliminate wear to the rifling.
In the time when that rifle was made, paper patching was still the preferred technology for the large-caliber military military rifles in Europe, and was preferred by many of the men who were finishing off the last of the buffalo in our western states. Paper-patched bullets do not lead barrels, and do not wear barrels, no matter what kind of powder is used nor at what velocity. The NRA's Col. Harrison wrote extensively on his PP experiments, which among other things pushed PP bullets to 3000 fps (in strong rifles!). Do some reading on paper patching. I'm sure Harrison's articles can be found somewhere. And I would be surprised if research did not turn up factory 40-82 ammo loaded with paper patched bullets.