Mike, I don’t want to open a can of worms here but you can safely shoot 2 3/4” shells in your gun without any alterations. In fact, several American makers in that time frame cut their chambers short but recommended shooting the longer shells. They wanted the hull to open inside the forcing cone in front of the chamber feeling that provided a better gas seal upon firing. And chamber pressures do not increase significantly. Out of respect for the age of the gun you might only use ammunition listed with no more than 3 dram equivalent and no more than 1 1/8 oz shot though I prefer no more than 1 ounce. Enjoy your wonderful gun! Sauer made fantastic guns!