This 37XC reamer is made by Manson Reamers. It is a floating pilot reamer. It has a .225 freebore which will accommodate both jacketed/leadcore bullets as well as turned solid bullets.
37XC reamer specs: .225 freebore (straight section) with a 1 1/2 degree lead angle for the throat
As of July 2020, the .225 freebore is what I recommend my customers use for the 37XC