You can use data for the 2 3/4 shell when loading for the 2 1/2" shell. All you'll have to change is the wad. You didn't say what wad you're using. I use Clay Busters and sub in CB- 1138 wad [ WWA12R ] meant for 1 3/8oz of shot - it has a shorter cushion to give the room you need for a good crimp.