Action question

[Standingbear]

Hello I have been a member here for awhile but never really post. Usually just enjoy reading all the good info. I am not a machinist but was wondering when you recut the internal threads on an action I'm guessing they will be an oddball size. So my question is how do you measure the inside threads to cut the right size threads on the barrel?

 

[Black Tail Hunter]

Out of curiosity why would you be re-threading an action? Are the threads damaged? It seems if you had an action you were going to rebarrel you would either buy a barrel with threads on the tennon that match your action or if it were a blank tennon then thread it to match.

 

[Daveinjax]

I'm pretty sure he is re cutting the threads as part of trueing the action. I'm interested in the answer also.

 

[Bugholes]

I'll use Remington as an example:
I bore the thread crest off, then re-cut the threads till a 1.072 plug gauge screws in completely. Then go very slowly till a 1.074 plug screws in with a slip fit- little to no wobble. I'll call this 1.075 on the action and stamp it so on the under side of the action. When I install the barrel I'll make the barrel tenon 1.072 and the install is clean and consistent. I feel better knowing its to a standard rather than cutting till the threads are clean and using a plug set to determine tenon size. It's more for the next guy rather than me (next gunsmith)

You can also thread with a full profile threading tool till you get the fit you want, but that's slow and a little more hobo than I'm willing to do

 

[Standingbear]

Thanks Bugholes that is what I was curios about. I was thinking you would cut till the threads were all cleaned up then try to figure out what size it was to match. Make more since to do it how you explained.