W W GREENER !@ GAUGE MUZZLE SIZE

[xkkat]

Hi, guys Just working on a Greener SxS with 30-inch tubes On measuring the muzzle end inside diameters I get .700 inches and .701 inches. Seems pretty tight to me Anyone have an idea what the gun was made for?
Wall thickness is 0.55 inches and 0.57 inches Barrells are in perfect nick and the gun locks up tight The gun seems on the heavy side to me. The serial is 75393
The flats show BP -BV - NP proof marks The Rib has the Pall Mall address on it
any help appreciated Regards Xkkat