Is pounder the correct description for these stone tools??? It implies a striking action - surely they are used with a rocking/grinding action - stone is relatively brittle, and does not withstand impact well - even light blows, if repeated can break it (c.f. flint knapping with antler or wooden strikers)...
The handle forms on many look as though they would also be rotated, c.f. stone corn mills (quern) see:
http://www.angelfire.com/journal/mil.../handmill.html