Could be that a steep curve is not making full contact. I came to that conclusion about some round head hammers that I have. Also true with too light a hammer. (When I use a light hammer it sounds like do-do.) Or it could be the pad. I've had remarkably different results with different pieces of leather.
I look at hammers like anything else. I take good care of my stuff, but if I'm not using it, what's the point? (Yes, it's true. I am living on the edge. I even use china as everyday dishes! bah-ha-ha! The devil may care!