When I guided folks bird hunting back in the day, I always insisted that they keep their hunt with me "gauge specific". If they wanted to bring two guns, that was fine, as long as they were both the same gauge. It was no great brainstorm on my part, it was what my gun safety intructors had taught me as a kid.
I remember one of the regulars on the "Purdey and port" board spilling his guts about how he had done the same, and how he was going to give up shooting the gauge of whatever cartridge had lodged in the bore (after he put it there) to avoid the problem. Seemed like a bit of overkill, but, if thats what it takes, I guess. Like the Honda ads say, "Stupid hurts".
Best,
Ted