Giant Extruded Powder Sticks for Huge Naval Cannons

Story by Boyd Allen
While many top competitive shooters trickle their stick powder charges to a kernel or two, that would be impractical when loading charges for giant naval guns. You may be surprised, but the shells fired by the U.S. Navy’s massive 14″ and 16″ naval guns were also propelled by stick-type extruded powders. You couldn’t trickle these ‘kernels’ though — a single stick or ‘grain’ can be over 2″ long.

The U.S.S. Iowa fires her massive 16″ main battery. The U.S. Navy’s Iowa-class battleships carried nine huge 16-inch Mark 7 cannons in three turrets. The big naval guns were 50 calibers long, i.e. 50 times bore diameter, making the barrels 66.7 feet long from chamber to muzzle.

In connection with a Benchrest Central discussion that drifted to the subject of powders used in large naval guns, I heard from Joe McNeil, whose father was involved in manufacturing those very propellants as a DuPont employee. Joe writes:

“My Dad worked for the DuPont company for over 40 years. Every time the nation went to war he was assigned to the gun powder plants which DuPont ran for the government for $1.00 per year! His last assignment was at the Indiana Ordnance Plant in Jefferson, Indiana from 1952 through 1958. He had a display case made of all of the different powders made at the plant and left it to me. That’s why I have a grain of 16″ gun powder. He took me out to the Jefferson proving grounds once when they tested the powder in a 16″ gun. We watched from a half-mile away but it left a lasting impression when they fired that gun. They actually had a set of rings they fired through to test the performance of the powder and shell. This was a truly fond memory of my Dad and his work.”

Here are some pictures of the gun powder “grains” made during the Korean War at the Indiana Ordnance Works where Joe McNeil’s father worked.

Above is the display case with the different powders manufactured at the DuPont plant. They include: 37 MM/AA, 75MM Pack Howitzer, 50 Cal. 5010, 20 MM 4831, 30 Cal. 4895, 76 MM, 3″, 5″, 90 MM, 4.7″, 240MM, 8″, 280 MM, 175 MM, 155 MM Howitzer, 155 MM Gun M.P., 8″ Gun M.P., 12″, 14, 16″. There are different-sized ‘grains’ for specific rounds.

16-inch/50-caliber gun projectile plus six propellant bags. Display mockup aboard U.S.S. Iowa (BB-61) in San Pedro, CA. Photo by James Madison per Creative Commons CC-BY-SA-4.0 license.