The instructions explain it pretty well I believe. But this is how I do it.
The insert screws in and out to change the headspace. The total length of the plug will end up being close to 1.730” - so start close to that.
Measure the length of a 209 primer first.
Loosen the set screw on the barrel end of the plug
Install the plug
Insert the 209
Attempt to close the action and see if it is contacting/crushing the primer slightly, if it seems close then close completely (do not pull the trigger)
Open and measure the length of the 209. It should be about .003-.007” shorter.
If necessary, screw the insert in or out to achieve the desired .003-.007” crush
Carefully remove the plug and tighten the set screw.
Then measure the length of the adjusted plug for future reference.
Hopefully this makes sense. Feel free to pm me.
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