0.224" - Marlin 336 in 219 Zipper 0.243" - Winchester Lee Sporter in 6mm Lee Navy 0.257" - Marlin 1893 in 25-36 Marlin 0.264" - 1st Model Newton in 256 Newton
EDIT: While I once owned a Winchester Lee Sporter in 6mm Lee Navy, I never had occasion to shoot it and I'm not sure that the bore diameter was 0.242", 0.243", or 0.244".
Last edited by 260Remguy; 01/10/20. Reason: Added comment