I believe wood was used more often than one might suspect as finding the right horn tip with the right color can be like looking for the holy grail.
Any thoughts on the materials used, etc?
Gary,
I have no idea how many screw tips were made from wood rather than horn. However, I believe you are looking at this from a 21st century perspective which may be putting a slant on your thinking.
I know that, in todays world, a lot of horners are having problems with finding suitable horns to make into powder horns. The people who have been able to find a supply of horns are selling them at inflated prices which usually preclude a horner buying a large supply of horns at one time. On the other hand, during the 18th century, horns seem to have been readily available to professional horners and the horn factories. These professional horners and horn factories most likely had hundreds of horns out back in a shed or stored in the back of the shop. I believe there was no "looking for the holy grail" back then. A short walk to the shed out back or the back room of the shop or factory would reveal horns that were suitable to make screw tips from.
Black horn material for making screw tips and applied tips is rather easy to find. Instead of using ebony wood, just "Google" knife making supplies and look for horn "rounds" that the knife makers use for making round knife handles. The rounds are usually 4" to 4-1/2" long and come in various diameters. Example:
http://www.texasknife.com/vcom/product_info.php?cPath=587_588_598_866&products_id=1245Randy Hedden
www.harddogrifles.com