I recently bought a mossberg 835 used, the choke tube in it has no markings on it so I am wondering the best way to tell the size. I used calipers on the exit end and got .695
Sounds like the factory Mossberg choke.
Welcome to OG and congratulations on your purchase of one of the best patterning guns for turkey hunting. I agree, you probably have the extra full turkey choke that came with the gun. Depending on what shell you decide to shoot, the .695 will probably give you fair results but the 835 seems to pattern it's best with a .670 to .675 choke. The people on this Forum have plenty of experience with patterning of the 835 and are willing to share their Knowledge with you. Good Luck setting up your 835 and Good Hunting.