Thanks for the reply. It does indeed resemble an air chisel bit, but the size and shape are off. It appears to me it was factory made, and not re-purposed or home made. My wags have been, A possible captive screwdriver shaft with missing linkage, and a Possible special purpose factory, or machine repair (Special Purpose) tool, with the bulge being a stop or a guide???Don't Know! PS: will try to take and post side view soon.