The Seller states that it was used to get screwed into a gate to clear the outside from attackes. I am really sceptical because of never seeing something like it before. Was this really a Thing? 
I've never heard of any such thing, it sounds slow, inefficient & a waste of time when one could simply fire a musket through a small hole with effect. 
 
I suspect that this is a wood splitter.  Hammer it part way into the end grain, pass a bar through the eye & screw it fully in & then set it off via a fuze.  
 
google 'black powder log splitter' & similar searches.
		 
		
		
		
		
		
		
		
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