I did that one time. Taped about 6 of them together and shot them with a .300 WBY at 100yds and a 180 grn Ballistic Tip. What a mess that one made. Little itty bitty .30 on the front and blown up phone print all over the palce behind. Suffice it to say, it penetrated all of them with a nice 8" crater in the back.
FWIW, frozen pumpkins and watermelons are fun too. Those things absolutely explode. The funniest thing was that our range had a pumpkin and watermelon patch come up the next year. The melons didn't last that long though, too tempting a target I reckon.
