It all depends upon the composition of the bullet jackets. Expanding bullets with soft copper jackets were certainly used without problems in rifles prior to the widespread use of chrome-moly alloy steels for barrels.
However, there are soft point bullets that have jackets made with harder alloys for controlled expansion. So more research is needed before using them. For all the shooting I will do with my own .450 BPE double, I will just stick with paper patch or grease groove cast lead billets.
Full metal jacketed bullets typically utilize harder jacket alloys to resist deformation upon impact. Naturally, they would be more likely to cause premature wear in old barrels made from softer steels. Chamber pressures would also tend to be higher too, assuming equal powder charge, bullet bearing surface, weight, etc.
Remember too that bullets for Black Powder Express rifles are typically light for caliber. Usually on the order of 270 to 300 grains for .45 caliber. I started with smokeless for black loads with 4198 and dacron filler, but switched to all black powder because of concerns about ringing chambers. I've been dealing with the minor chore of cleaning flintlock rifles for years, so no big deal.
