Let us know how it works out, Griz. I hardly ever shoot Grandma's 1908 Hammerless any more because I just don't want to dump 18 bucks for 50 tiny little rounds. It's just as well, I shouldn't be shooting a hundred year old pistol much.
P.S. Maybe you can't overpressure a 25acp with common powders? Load tables show 17,000 to 18,000 psi with a compressed charge. Eventually you've filled the case to the rim and just can't hardly seat a bullet, but still don't exceed 20,000.
P.P.S. Maybe you don't even need a powder measure. Just use the primed brass as a powder scoop, then seat your bullet. Maybe you don't even need to buy bullets. Just use a small fishing sinker.