Many of the M71/84 rifles were effectively unused. By the time they reached the depots in quantity, smokeless powder had been introduced by the Frenchin the Mle 1886 Lebel, and everybody was racing to produce a smokeless powder cartridge rifle with a smaller bore. Like, for instance, the 8mm Kropatschek, which was basically a derivation of the M71/84. So the M71/84 was instantly obsolescent.
As to paper-patched bullets: there are two disadvantages that are mentioned among BPCR shooters.
1) There appear to have been cases of paper stripping off in the bore, leading to ringing of the barrel when the next shot was fired through the stuck paper. Sorry, I cannot quote sources at the moment, so you are entitled to treat this as hearsay.
2) The paper has a slight scouring effect on the bore. A friend who is a top competition shooter in his country has a rifle that has noticeably lost performance because of this. I have no interest in wearing out rifles that are active antiques, so I only use grease-groove lead bullets with about 5% tin. As was shown by Henry Pope, you will not cause any measurable wear in a long shooting lifetime by firing propery lubricated soft/medium-hard lead bullets in a BPCR. After the first shot, the GG-bullets are riding on the lubricant, not bare metal. Just don't use recycled wheelweights!
And, of course, the original M71 or M71/84 cartridges in their boxes are far too valuable to be shot!
Patrick