If I'm not mistaken, RST's are Cheddite hulls.
For my 2 1/2" hulls that I have cut down, I roll crimp them. I'm not in a hurry and it doesn't take that long to do. I have found that the old time crank roll crimper is very good and does a great job on Remington hulls. It is faster than doing it with the one in the drill press.
If you are reloading hundreds of 2 1/2" hulls then maybe you will have to rig yur machine to do this, as stated not hard to do.

These are Remington Gun Clubs, for some pheasant hunting.
I have found out that any load you find in a 2 3/4" hull that is 8 or 6 crimp will work in a 2 1/2" hull that is roll crimped.