Brownells Gun Tech™ Caleb Savant gives us an introduction to shotgun ammunition, commonly called shotgun shells or "shotshells". GAUGE is the diameter of the shell, and the higher the number, the smaller the shell diameter. So a 10 gauge shotshell is much larger than a 28 gauge. Bigger shells throw larger loads of shot, have more powder, and kick out more recoil. The two most common shotshell gauges are the 12 gauge and the 20 gauge, which give a good balance of load size and manageable recoil.
LENGTH Again, longer shotshells are more powerful because they hold more shot and powder. Length is measured after the shell has been fired, so an unfired 23/4" shell will be shorter than 23/4". A shotgun that can shoot longer shells will usually also shoot shorter shells; if it takes 3" magnum shells, it will also shoot 23/4" shells (usually). Shotgunners also pay attention to the length of the BRASS portion of the shell. The higher the brass, the more powerful the powder charge in the shell. "Low brass" shells contain light target loads.
SHOT SIZE The shot pellets inside also come in different sizes. The higher the number, the smaller the size of each pellet, and the more pellets there will be in the shell. (But remember, small pellets have less velocity and less mass to knock down targets.) What about Buckshot? Caleb explains that, too. SLUGS are large, heavy lead bullets fired from the shotgun, often used for closerange hunting or selfdefense.
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