I just measured the exit diameter of three Remington SP-10 factory choke tubes and got these dimensions: Turkey XFull (Lead Only) = .730"; Steel-Xfull-Lead Full = .750"; and Steel IM-Lead Modified = .770". These seem to be very large exit diameters unless Remington uses something like .795" bore diameter rather than the sort of standard .770" bore. Can anyone comment or help me understand what's going on here? If it helps, the shotgun that they came with was originally sold in 1996. It has the factory nominal 26" vent rib barrel. Many Thanks, Ed