actually, that is not a vent pick pictured. I am told it is a tool used when a friction primer broke off in the vent of a gun. It was used to push the broken brass primer tube down into the guns chamber, which then it could be removed with a scraper. The tool could be hammered on to push it down, if necessary, hence made of steel. And, the hole in the middle of the top is there so if the tool gets stuck in the vent, possibly from burnt powder residue jamming it or the broken primer, another tool could be used to slide through the hole and create a 't' handle to pull it up and out or twist it back and forth to work it loose.
These tools came in two different head styles, a hex head and an octagon, by the way.
A true vent pick for puncturing a powder bag had flutes on the shaft because after the powder bag was punctured, the artillerist was supposed to twist the pick opposite the flutes upon removal that way drawing up some of the powder into the vent hole, helping to insure ignition of the friction primer.
This is what I have been told from others, I wasn't there in '65 !! David