Is that is a Browning round......FN Herstal ...made in Belgium ?
Maybe a round from a B.A.R........? Browning Automatic Rifle ?...I dont know ...the round tip looks like a cross tip screw driver LOL
One thing I do know from my time in the U.S. ARMY Engineers(Combat Airborne) Before 1980..........That does not look like ANY blank cartradge that I have ever fired.........The blanks we used were Crimped at the end with NO Projectile sticking out !
Maybe some current,or retired Military can give you an Idea....Or maybe Law inforcesment ? Good Luck,,,and as always,,,Nice Finds,and Great Pix.........H.H.