a few of us were patterning guns this afternoon for turkey hunting using seven eights plywood to hold our targets. one fellow fired a round of number five shot and he got a nice shot pattern but unbelievably he blew a hole through the plywood about a foot to the side of the target . it looked like a slug had gone through it . i have never seen anything like it .the only thing i can think of is the wad went through the plywood. is this possible? this was some very old ammo possibly twenty years plus. any thoughts.