Please accept my apologies if I'm missing something here but I have to question why the .22 insert was placed in the right shot tube of what sounds like the more common drilling configuration - SXS shot tubes over rifle barrel? Typically with the rifle barrel "selected" the rear sight pops up and the front trigger now fires the rifle barrel and right shot barrel will not fire. In turn the rear trigger is still at the ready to fire the left shot tube with the rear sight still in its up position. This is why slug cartridges are used in the left barrel. If one is using optics I suppose one could put the insert in the right shot tube but it looks like the original plan was to use the rear sight.
