If you have/want something special Call the reamer manufacture and tell him what it is for and any thing different than SAAMI spec .
He will make recommendations and send you the reamer dimension for your approval before he cuts it.
He may request a dummy load (Bullet, but no powder and primer loaded to the COAL you want and with the bullet you want to use.
He can assist you in free bore and throat dimensions.
Cut out the middle man and go straight to the reamer manufacture to buy your reamer, that way you lessen the chance you get a reamer that is not what you want.
I like to use Dave Manson @ Manson precision reamers for the service and quality. PT@G also is a good one but sometimes his service is less than stellar.
J E CUSTOM