Beartrack

In the late 19th and early 20th century there were many ammunition manufacturers that made cartridges without a headstamp. Probably had to do with legal questions since most cartridges of the time were what we would call proprietary today. Many of these cartridges had certain characteristics that were unique to the maker, such as raised rings, slightly convex or cocave heads, rounded or square rims, etc. A serious cartridge collector might be able to look at the one you have and identify it as to maker. But, it's probably a long shot at best.

Ray