FIELD NOTES / 01-06
Read the markings.
Understand the language.
A few distinctions make an ammunition reference much easier to read.
Caliber and cartridge
Caliber describes a bore or projectile designation. A cartridge name identifies a particular ammunition design. Similar numbers do not establish that two cartridges are the same.
Rimfire and centerfire
These names describe ignition systems. Rimfire priming is contained within the rim; a centerfire cartridge uses a primer located centrally in the case head.
A standard and a factory product
Standards describe dimensions, limits and test procedures. Bullet mass and published velocity belong to a specific factory product and its test conditions.
Grains are not grams
The abbreviation gr means grain, a unit of mass. One grain equals 0.06479891 grams. Keep units visible when comparing specifications.
Gauge and shell length
12 gauge identifies a shotgun bore category. A complete shotshell designation also includes case length. The length refers to the opened case, not simply the closed cartridge.
Reading sources
Start with official standards and manufacturer documentation. Historical catalogues establish what was offered at a particular time, not what is still in production.