I wish to start using jacketed 8mm bullets in my 1867/1889 8X58Rd Swedish Krag. I realize these rifles were rebarreled to use this FMJ smokeless round, but I keep seeing disparaging remarks about older barrel's abilities to do this. Will reasonable loads using IMR 4198, Unique, H4198, or Reloader 7, perhaps with heavier bullets, harm accuracy and hasten deterioration? How about with other older rifles, in general? I will welcome all remarks, to include experiential loads for this old smokepole, which has a pristine bore. Thanks in advance.

The barrel was intended for jacketed bullets, whether cupronickel or copper I don't know. I'll just have to experiment. Thanks.

Not quite as old, but I shoot jacketed in my .348 with good accuracy.  It's my great grandpa's rifle, and the only real issue is that someone in the family didn't think much about cleaning the bore, so it's pitted pretty badly and attracts copper fouling like crazy