U.S. Army Yuma Proving Ground weapons operators ram the MK 437-equippped round into the five-inch Navy gun tube. "The big challenge was getting the Navy gun tube set up on something that isn't a battleship," said Adam Rinne, test officer. "You can't ...

YUMA PROVING GROUND, Arizona - Lot acceptance testing, the testing of a sample of artillery in real-world conditions to ensure reliability, is an important part of the U.S. Army Yuma Proving Ground's ground combat workload.

Less well known, however, is that YPG conducts lot acceptance for Navy artillery and fuzes.

Recently, the MK 437 multi-option fuze for use by the Navy was extensively tested at the proving ground.

For a munition to detonate when and where necessary, a fuze is vitally important. It both triggers a detonation and has safety features that keep gun crews safe by preventing a shell from exploding while being handled prior to firing or detonating too soon.

There are fuzes that can be set to detonate a shell at a preset time in flight, when it detects a certain distance from the ground or a structure, or when it hits a target. The Army's M782 multi-option fuze combined all these potential fuze settings into a single fuze that can be used on either 105mm or 155mm howitzer shells. In the last decade, the Navy wanted a comparable multi-option fuze compatible with their guns and developed the MK437, as a result.

Though a naval system, in many ways YPG testing was similar to artillery evaluations performed for the Army: high speed cameras shooting thousands of frames per second capture crisp images of the projectile leaving the tube as it fires, and television cameras far downrange capture the round's detonation. The muzzle velocity of the round leaving the tube is measured, and the round's accuracy is scored. Yet, there were differences.

"The big challenge was getting the Navy gun tube set up on something that isn't a battleship," said Adam Rinne, test officer. "You can't park a battleship at one of our gun positions."

This challenge was met by mechanics from YPG and the Naval Surface Warfare Center Dahlgren Division. Even after this, the seasoned crew had to adjust to differences in firing Army and Navy rounds. For example, there are non-combustible parts to the Navy round's propellant that can eject from the muzzle when fired. This debris is harmless, but its presence was initially unfamiliar to those accustomed to Army howitzers.

All in all, however, the test was a groundbreaking endeavor for all involved.

"It's been a good experience," said Larry Liberman, fuze design agent for the Naval Surface Warfare Center Dahlgren Division. "Once we got the test going, YPG was really efficient."