Gunworks Un-Bored Delrin Bush (plastic) only

Gunworks Un-Bored Suppressor delrin bush with spanner flat edges

How do I find out what diameter I need to bore my bush out to?

Easy, put your Gunworks suppressor onto your threaded rifle (rifle must be threaded to get an accurate reading) and screw the suppressor on until it is nice and tight on the barrel.

Use verniers to measure the diameter of the barrel where the suppressor finishes (see pics) you can place a vivid pen mark at the same spot and remove the suppressor to take the reading if you wish