IMHO it depends on the monometal bullet design, metal and make more than on the age of the gun. The bullets must be made of a soft metal , copper, be sufficiently grooved and made by a reputable maker. I use Barnes TSX and TTSX bullets in 3 drillings, 7x57R and 8x57IRS, a 9.3x74R double rifle proofed 1919 and another 1880s one in .500 -.450 #1 BPE without evil effects so far. But I shy away from any monometals without grooves like the first generation X, or those made of brass or by small inventors. I never tried such like the Impala "voodoo" bullets, but for other reasons as well.