Originally Posted by
rockrat
Looked down a few cannon barrels at Ft. Sill, OK and the twist of 1 in 25" didn't seem right from what I remember of the barrels of the smaller cannons there. Using the Greenhill formula for the 16" projectiles, I suspect the twist is 1 in 25 FEET , not 1 in 25 inches. Was checking online and saw the specs where the twist was 1 in 25 for the 16" guns, but curious as the tables didn't specify what the 25 was, so I figured to just plug it into the Greenhill formula. Got on the Mountain Molds website ,but their tables only went to 1 in 15 feet, but since the formula was there, I plugged in 300"(25 feet) as the twist. Came out to max. projectile length of 128", well over the 72" projectile length for the 16" AP round.