Daryl, add a photo of the top of the tool, head on pic. If the hole runs through it then it is not a short starter for a false muzzle. I personally don’t think it is but let’s see the top. If it were a starter I think it would be a solid rod closely fitting the bore diameter of the false muzzle. And it certainly wouldn’t have the bell bottom yours does.
Here’s is a link to what a false muzzle and its starter looks like. Not even in the ballpark with your tool.
http://www.hallowellco.com/false_muzzle_and_bullet_starter.htm
