After quite a few years I am really getting tired of posting this over and over and...............
THERE IS NO "MODERN .32-20 AMMUNITION" FOR RIFLES ONLY!!!!!!!
.32-20 was and is a rifle cartridge, since it's introduction for the Winchester model 1873 in the 1870s. However it was first adopted for revolver use by Colt in 1882. ALL CURRENTLY MANUFACTURED .32-20 ammunition is safe for use in any revolver in good mechanical condition. Any commercial ammunition of any period with flat-point bullets, whether Lead or jacketed, is appropriate for revolvers.
There was at one time a single load specified for RIFLE USE ONLY, and that was an 80 grain load with a jacketed round nose hollow-point bullet that looks like this one below. As Art Doc pointed out, this type ammunition has not been manufactured for decades. I have seen dates from the 1960s clear back to pre-WWII for the end of production for it. The head stamp usually would be H-V, Super Speed, or something similar to indicate it was for 1892 and similar rifles, it was not for model 1873 Winchester rifles.