Consistent ammo adds a lot of pleasure to my slinging.  I know variations in shots come from variations in technique only.  Also, I size/form the ammo for best results. 

I "roll my own" from already-wet potter's clay from a craft store.  11,250grams for $15.  I slice/dice it into 76gram chunks, hand-roll the chunks into mini-footballs, then let them dry to 65grams.  I should get about 150 glandes, for $0.10ea.

They're tougher than you think, and dont shatter when they land on a lawn, so can be reused.  Problem is that they fly so well/far, it's tough to find some of them.  But if I cant find them, I dont worry.  They're made out of "dirt" anyway.

FYI   mgreenfield

The clay I got was a 25lb box labelled "Moist Pottery Clay X-15", packed by AMACO, ....American Art Clay Company, Indianapolis IN.   As long as you keep it in the plastic bag it comes in, it seems to stay plyable.

Dried glandes made from this clay are 85.5% the weight of the moist material you start with. 

I just rolled 60 little clay footballs at 24grams wet.  They'll be 0.855 x 24 = 20.5 grams dry.     mgreenfield

If you have a hole, an old bathtub or a 45 gallon drum (55 to you most of you) You should be able to "pit fire" glandes in batches of a few hundred or so. Google.

Matthias

A local place called 'The House of Clay'... not sure what type it is but I can make a call Tuesday and find out. It's gray in it's raw form and almost chalky white when dried in the sun.... When I went to pick up the 25lb bag I just told the lady cheap clay would do fine. That lead to a long question and answer session about slings and ammo. I figured I'd lose the clay glandes as fast they could be made so why bother fireing the clay...