You can load 2 1/2 inch cases w/o changing any adjustments on the loader at all if you use a different crimp.
Start with your cases shortened to 2 1/2"
Load as normal on your progressive (or single stage) loader.
Use the same load recipe as you use in the 2 3/4" case.
The difference in the shell length ( 1/4") is in the crimp area and can have nothing to do with the capacity or load if you use the following crimp style.
When the hull has been loaded with the shot, you need at that point to add one simple step to the process.
You place a thin cardboard overshot wad on top of the shot charge before the crimping is done.
A 20ga overshot wad works well in 12ga loads, or you can cut/punch them yourself from card stock, milk carton type material. They do not have to be a tight seal in the hull. They just have to cover the center area of the shot.
When the round is crimped with the normal 'star crimp' by the machine, the shortened hull will leave a hole in the middle of the crimp on the end because of the cut off length.
That over shot wad that you placed there is under the crimp and prevents the shot from coming out.
There is more than enough of the original shell left after the 1/4" is trimmed off in the shortening process to still give a good solid star crimp. It's only missing the center section which the over shot wad covers up.
So you have a 2 1/2" shell (length when fired),,an easy way to load it w/o any adjustments to the machine,,and only the overshot wad to be placed on top of the shot after it is dropped into the hull and before the hull is crimped.
Load 2 3/4" shells right along w/o doing anything to your machine.
