Hi, I'd advise against shooting modern loads in your fine old pair. If your gun was proofed for 2 3/4" it was proofed for 9682 psi. Pressure is what you have to be concerned about, not shot charge. Modern loads are for the most part 11,500 psi.
While the action maybe able to take these loads, I wouldn't shoot them for fear of damage to the action and stock after repeated use of modern loads.
I'd heed Rocketmans and the others advise and stick to known low pressure loads.
Better safe than sorry!
All the best and I hope you have many happy and healthy years shooting them!!
Greg
