Ron that looks like a real "sweetie"! With Bruce's photo I think you can see what you can do without special shells or reloading equipment. My only suggestion would be to stay away from the Wally World and similar cheapie loads as they are designed to function in anything. Many times the pressures are kept high to achieve this. I would stay with target or field loads of 1 1/8 ounce or less and pressures around 9,000/9,500 psi. Some ammo companys will give you the pressures of their shells. The big concern is more for the wood in the stock where it joins the metal frame. Remember it is very old and possibly oil soaked enough to make it soft. Putting heavyloads and recoil through the gun can cause the stock to split. I would not alter the chambers as this isn't really necessary and there may not be enough metal in the barrels to do this and keep them safe to shoot. A really good "smith" can measure the wall thickness and make that determination. Remember, the shells we now have are so much better than the ones used when your gun was new it shouldn't require using more than a field load to duplicate what was a "heavy" load in those days. Lee.
