The bushing they refer to is in effect the vent liner. Standard vent liners are steel screws with a small (.03") hole drilled through them. They erode over time depending on the powder type and charge being used. The bushings are made of tungsten carbide and are held in place by a set screw (lock ring) with a larger hole through it. The bushing material resists erosion much better and lasts longer than the steel vent liners.

BTW, the wrench is in the mail


*Whoops, Overkill beat me to it.

Last edited by tmitch; 03/24/16.
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