16 Ga. Skeet Shells

Hi Everyone...I just bought a new box (OLD STOCK) of XPERT 16 Ga. "Super Skeet Load" Mark V red plastic shells. These are loaded with 2 1/2 drams of powder and have 1 ounce of #9 shot. The production # on the inside flap is: H31XM92. Wondered if anyone might know when these were made?
MANY THANKS!!!