the best billets are not from sheds, but from antlers which have been cut off the skull. Ideally, they should be cut close to the skull, as that is the densest part. If they are from sheds, the less weathered, the better. the best way to get billets is trading. Figure out what you have that may be rare in places where moose live- I have traded some moose for obsidian it was a great deal for us both- he lives where there are moose but no obsidian, I live where there is obsidian but few moose.
The one I use most is about 1 3/4 at the widest part and 6 inches long. with this I can take flakes in obsidian up to about 4-6 inches long. I use it to make bifaces from 4-10 inches or so and on the finer flaking of bigger pieces. For longer flakes, I have a big one that's 2 1/4 dia and 8 inches long- with this I can make obsidian flakes the size of my whole hand. I use it for roughing out really big stuff and for large flakes on early stage bifaces in the 5-15 inch range. On the smaller side, I have one that's 1 1/4 dia, used for small flakes of an inch or two.
