Let us not abandon all hope yet. The projectile in the post above is the M59 APC round for the US 37mm antiaircraft gun. I have only encountered that one projectile. However, I was into the M3, M5, and M6 antiguns at the time, so I went ahead and shot it. Are you looking for an M59 specifically, or do you desire the M51 AP round for the M3, M5 and M6 guns? I do hereby declare myself the king of ammo for the US M3, M5 and M6 guns with over 50 original projectiles and 200 casings for such guns. I do have a spare an M51 round of your choice, B1, B2, etc. I would love to trade one for a 2 pdr projectile. Do you think such a projectile would survive post from the US to the UK?