I have a Gunline barrel bedding tool with a 3/4" cutter. It's designed to form an accurate barrel groove on the gunstock.
You can see what it looks like here: http://www.midwayuk.com/epages/Midwa...roducts/191692
The one I have is - from everything I can see - completely unused. There is some discoloration on the forward of the chrome ferrules, but this doesn't affect usage.
Both stocks I have are synthetic, so not quite sure why I bought this