HILL AIR FORCE BASE, Utah — Every military base accomplishes important missions. While some missions are very visible, others are little-known and performed in out-of-the way buildings separate from the main installation. Here, the flight training mission is very visible whereas the gun shop mission is less evident.

The 531st Commodities Maintenance Squadron gun shop is located down a narrow road on the base’s east side. The shop’s aircraft ordnance system mechanics perform depot maintenance on 20 mm and 30 mm aircraft guns. They deliver reconditioned, test-proven guns back to warfighters from every military branch.

“The gun shop is the only facility on Hill Air Force Base capable of overhauling and supplying the Air Force, Navy, and private sector with 100 percent reliable 20 mm and 30 mm aircraft Gatling guns and handling system components,” said Bob Migliore, 531st CMXS director.

Whether routed to the gun shop through the supply system or removed from depot aircraft by the shop’s mechanics, all incoming guns are disassembled and inspected upon arrival. Guns passing all inspection criteria are then moved along through their specific overhaul processes.

The majority of 30 mm gun parts are replaced with new components. Twenty-millimeter guns require more intensive inspections and work.

“All 20 mm housings and rotors are inspected for cracks and worn cam paths,” said Ken Van Dyk, the gun shop’s Evaluation and Inventory inspector. “We determine if a gun can be fixed or if it must be condemned.”

The reconditioning process is long, but the results are worth the effort.

“Work control documents for the housing and rotors are 20 to 22 pages long, so they go through a very thorough process,” said Van Dyk. “Our goal is to have a gun that is as close as possible to brand new from the manufacturer.”

All maintenance and testing procedures are performed in the gun shop with the exception of welding and surface finishing.

This has not always been the case.

Prior to construction of the current gun shop building seven years ago, testing of 30 mm guns was done at an open-air facility on the Utah Test and Training Range.

Doug Stutzman, the gun shop’s work leader, said testing at the UTTR was inefficient mainly due to administrative requirements and travel time.

Today, all overhauled guns are tested in the bunker-like indoor range attached to the building’s north end.

“Here, in this facility, we can build, test, and put aircraft Gatling guns back into the supply system faster than before,” said Stutzman.

Visitors to the gun shop are often most impressed when they witness a test fire.

In preparation for test firings, guns are mounted to stands, gun barrels and ammunition chutes are attached, and targets are placed downrange. During tests, guns are fired remotely by a technician operating inside a control room separated from the range by a safety door.

Each test can be observed on a bank of monitors inside the control room and despite the range’s sound-deadening construction, each test can be heard. If seeing and hearing are not enough, floors and walls shake while the guns are fired so everyone knows a test is underway.

“Due to pressure and vibrations produced during a 30 mm test fire, all screws, nuts, and bolts on the safety door have to be checked,” said Stutzman.

Each test happens very rapidly. The longest test fire is under two seconds.

Although 66 to 100 rounds of ammunition are fired during each test, the bursts are short and the reports are so quick in succession that the rounds cannot be counted audibly, even at the slowest firing rates.

“Twenty-millimeter guns are tested using 66 rounds. Six are fired for an operational check, and then 60 are fired for qualification,” said Van Dyk.

Stutzman added: “One hundred rounds are used to test and qualify a 30 mm gun. Ten rounds are fired for an operational check, followed by 50 rounds at full firing rate, and then 40 at a half rate for qualification.”

Once a test is complete, many visitors have walked through the smoke and dust inside the range to look at what is left of the ragged target. According to Stutzman, most are amazed at the process and the most frequent question he’s asked is, “How do I get a job here?”