Sorry Perry, but I had incorrectly assumed that you probably knew the reason to avoid shooting the low cost Wal Mart type promo loads in your vintage doubles.
These typically cheap low brass shells can actually produce peak pressures equal or greater than many higher dram equivalent high brass shells because one of the ways the manufacturer keeps the cost lower is by using smaller charges of faster burning powder. The result is a higher and quicker peak pressure, something to avoid if you wish to shoot vintage doubles with the type of loads for which they were designed. Pressure has virtually nothing to do with recoil other than the fact that it is pressure which produces the velocity of the shot. Shot charges of promo loads are usually smaller than most high brass premium loads, but the velocities are right up there, and the recoil impulse can be a little hard on 100 year old wood.
That said, many of these old doubles have been used with anything that would fit in the chambers. Of course, many are loose, off face, and worn out for a reason too. Since we know better, it is prudent to give them the proper diet so they can last for many more years. An Indy car can go nearly 200 MPH. But they rebuild the engine after 500 miles if it finishes the race.
