They are principally for identification of the load. Example: a 125 Gr. JHP, a 147 Gr. JHP and 158 Gr. JHP in a smooth case would look identical. The case cannelures allow identification once the ammunition is out of the box. Same with DEWC and HBWC loads. They are not universal between manufacturers.

The cannelures do not indicate any differences in the cartridge case itself.

For re-loaders the cannelure patterns can be ignored unless the individual wishes to segregate empty cases by this feature. One example is some re-loaders wish to load wad-cutter ammunition in cases originally factory loaded as wad-cutters. The cannelures, normally three in this case, allow identification of those cases that were factory wad-cutter loads.

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Gunsmithing since 1961