Forgive me if this question has been asked before.

I would like the contact information for someone who can measure a bore slug that will have 3 lands and grooves on it. My trapdoor is in need of a correct sized bullet mould so that I can shoot the right sized bullets out of it.

Thank you for your time.

I know that this takes a special type of 3 jaw calipers, that's why I'm asking.

Bubba, there is a man who does this service for free- just send him a SASE for his reply to you, along with the carefully packaged bore-slugged bullet.
Here is the info:
O.H. McKagen
9229 Arlington Blvd.
Fairfax, VA. 22031
Hope this helps.
Emery