Lyman short J shell holders

[Scoutdog99]

What was the purpose of having both long and short Lyman J shell holders? Did some tools at the time only accept the short J type shell holders? I’ve always wondered, but don’t know why.

[Pressman]

The J shellholder is part of the Armory and Tru Line presses. They used a short shellholder do to the base thickness.
The longer shellholders came with the Ezy Loader and Tru Line Jr presses.