There are things you can duplicate, you can use the Rem hull, probably find some Rem primers and certainly can find the figure 8 wads. You can buy the best/hardest shot you can find. I read from time to time folks are even buying the Remington shot. Powder is the best kept secret in the world that seemingly no one can or will identify or even tell the "parameters" of its specifications. That seems to be like the special blends of Whiskey, Tea, Coffee, Pepsi, Coke and so on, They could tell us but then they would have to kill us. The 1300 fps is something though you can safely duplicate if that is your objective. If you do not have one already get yourself a Lyman 5th edition and look under "Field Loads". The velocity is available but you will need to buy the various powders, primers, wads etc that the book indicates will produce the velocity and still be at safe pressures. I have duplicated velocities for the Nitro27 and Sporting Clays that way..... not sure it helped much but it was fun........... Larry