I have seen a birdshead gripped SA at my gun shop that is smaller than the standard "Model P" SA clones. These are in .32-20 and .38 Special only. I think these are the "Model P Jr." and Lightning models. Have not yet seen any .41, but wasn't really looking, either.
These do appear to be the same size as the old Colt Model 1877 rod ejector double actions. They are, of course, single action only, to comply with SASS regulations.
Incidentally, these are not all birdshead gripped as there are some smaller ones that have the traditional "plow handle" grip.
Bob Wright