A buddy of mine game this to me for Christmas. From what I can tell, it's a 4"-50cal. shell, mfg. in 1918. It's got anchors stamped in it so I'm guessing it was fired in a Navy cannon. It's 35 inches long, brass and the projectile weighed a cool 33 pounds. The max range was 15,000 yards! I love guns and extremes and this thing makes me giggle. I can only imagine the sound!!!
AR for scale.
AR for scale.