Based on a Belgium proofed 16ga. I have, I agree with two numbers on the same barrel being bore and choke.

Mine is stamped 17.0, or .669 inch on both barrels. The left barrel is stamped 16.4, or .645 inch, over the 17.0 and the right barrel has only the 17.o. The right barrel is, in fact, bored cylinder and the left is choked full using an inside micrometer with a 3.5 inch reach.