Shotguns
Inserts for shotguns are called subgauge inserts, and function in much the same manner as inserts for handguns or rifles. However, due to the nature of shotguns, the implications of using an insert differ.
Since shotgun shells are all straight walled, a change in chambering means a change in diameter of the shell. However, since subgauge inserts are designed to be used with shot, not slugs, the shotgun's barrel can continue to be used, with little or no impact on patterning. Many makers offer longer inserts, though due to the variations in shotgun bore diameters, these usually require custom manufacture.
Rifled inserts are also available, to allow the use of handgun cartridges or relatively low-power rifle cartridges.
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