I have found that you can use the Lee .38-55 Factory Crimp die on the loaded 9.5 x 57 MS rounds by using washers of appropriate thickness as a spacer between the top of the shell holder and the collet crimping sleeve of the die.

BUT I haven’t yet got to the range with my chronograph to find out what difference applying a “factory crimp” will make to velocity.

Anyone yet tried the .375 Swift 250 gr. bullets in their 9.5?