Ive had this tool for years but have absolutely no idea what it is for . The end opposite the tommy bar appears to be a screw driver? the internal end is countersunk with a hole through the end of the tool around 1/4” in diameter and it has Pickavant 280 on it. I know some of the members like this type of post and may be able to help. Did wonder if it was for installing spoke nipples but not sure the hole would be large enough?