1 1/4 is a fairly stiff proof and your gun should be quite heavy. Is the chamber itself that long, or does it just have a long forcing cone? You need a tight-fitting chamber gauge, or a dial bore gauge to tell where the chamber really ends and the forcing cone begins. If it just has long forcing cones, that's probably a later add but a good thing. If it has true 3" chambers, then someone has lengthened them from 2 3/4" and that's a bad thing. Have the wall measured at the end of the chamber...it needs to be 80 thou or more to be shootable. BTW the 16/1 and 14/1 are the original muzzle diameters, indicating a .669 and .701 muzzle, ie 60 thou (yikes) and 28 thou constrictions.
