Pressure is not the problem with a 1947 LC Smith, recoil is, and recoil is determined by the velocity and the weight of the shot charge. Recoil causes stock cracking unless the head of the stock has been glass bedded. 1 1/8 oz at 1200 is a 3 dram load, and is more than I like to use in my LC Smiths.
L C is very poor design insofar as recoil and set back into the stock wood. A 1 1/8 oz load at 1200 is well within capablity of other designs of the period. Your best bet is to sell the L C before it cracks and buy a parker, fox, Ithaca, nitrospecial, western arms. None of them have to be glasbedded to shoot moderate loads.
