Stop ring bullets were popular with Schuetzen shooters in Europe back when it was a popular shooting game 1890-1910 (rough time span). Many of those shooters loaded their own ammunition. The ring on the bullet body (see image below) "stopped" the bullet from dropping into the cartridge case. That's way over simplified but gives you an idea of how/why they were used. A few shooters today still use stop ring bullets to shoot their original European Schuetzen rifles.

Kirker wrote on Jan 28^th, 2025 at 2:06pm:


Why would you think that?

The ring not only stops the bullet from entering the case deeper, but also seals the bore to stop expanding gases from passing and leading the bore. So the design doesn't cause leading, it stops it also.
Another advantage of a stop ring bullet is to allow fixed ammo to be used in rifles with larger than normal groove size. So for instance a .32-40 with a large groove of say .327" wont allow a fixed bullet to be seated and still chamber in a .32-40 chamber, but using a stop ring bullet with a band of .327" or slightly larger and lower bands of around .323" will seal the bore, yet still chamber fine.