AMI Defense aims to produce higher-quality firearms through casting

PHOTOS COURTESY OF AMI DEFENSE

Tom Owens, senior firearms development for AMI Defense, says the company produces stronger, higher-quality firearms through its casting and testing processes.

The La Porte, Indiana-based operation falls under the umbrella of Aero Metals, an investment casting company with a 75,000ft2 factory and roughly 300 employees.

AMI Defense, the munitions branch of the company, produces 1911 frames, AR hammers, triggers, and more.

Once a design is finalized, the company produces a mold that gets injected with wax. The resulting wax pattern is then placed on trees and dipped in a slurry of compounds that creates a shell. The shell goes into furnaces and the wax gets burned out – the pattern melts out of the shell and metal is poured into the shell in its place. When the metal cools, the parts are cut off the metal casting trees and machined until finished.

AMI Defense differentiates itself in the market by using hot isostatic pressing (HIP) in the production of its frames and slides.

“We’ll HIP those to help collapse any voids postentially in the frame,” Owens says. “That makes it stronger. We hot press the frame to make sure they are straight before we machine them. A lot of other places don’t do that, but because of that, the end product is so much better. It creates a nice, strong, uniform, and well-machined casting of whatever we decide to do for an end product or an end item.”

The company’s frame design is built to adapt to new features the industry requests. For example, Owens says AMI Defense can produce a smaller magazine well to better balance the grip of the firearm.

“We’ve done a high undercut of the trigger guard, so it’s really comfortable in your hand,” he says, adding that the company tries to offer customers additional features they would commonly pay extra for if they took the firearms to a gunsmith for adjustments.

“We’re doing it for them, which helps keep the price down, and they get more bang for their money,” Owens says.

AMI Defense also uses 17-4 stainless steel, which Owens says is stronger than aluminum.

“Our 17-4 has a RC hardness of 34-36 and our 4140 carbon has an RB of 90-100,” he says. “This is stronger than aluminum but still allows for machining. The tensile strength of our 17-4 frame has a 150KSI with a yield of 130KSI. Our 4140 carbon has a tensile of 180KSI and a yield of 130KSI (the bending and tearing of the metal).”

The company uses a variety of equipment to finish its firearms, including Blanchard grinders, CNC milling centers, coining presses, and glass bead blasting.

AMI Defense has also tapped American Metal Testing to ensure its finished products are defect-free. American Metal Testing X-rays AMI Defense’s components to provide insight into the quality of the pour in the foundry and what voids might exist.

“They take photos and X-rays to look for cracks that might have developed,” Owens says. “That way we can avoid all of that stuff in our process by doing quality control checks, so we get the strongest, most condensed product that you can get.”

American Metal Testing is certified through the National Aerospace and Defense Contractors Accreditation Program (NADCAP), an industry-managed program evaluating and accrediting the specialized processes used in the manufacturing, testing, and maintenance of aerospace and defense components and systems.

This is important, Owens says, because it ensures a high level of consistent quality that’s expected of critical components, such as those included in firearms.

AMI Defense also performs its own testing, including straight trigger and curve trigger fire control groups for its AR-15 sporting rifle. The company conducts drop testing that exceeds minimum requirements, where a standard drop test must be 3ft on a concrete surface with a 1" foam pad. Owens says AMI Defense has eliminated the foam pad and instead performs drop testing at 5ft or 6ft on compact limestone.

“I just completed a drop test video that I even dropped the sporting rifle out of my front-end loader tractor at around 12ft,” he says.

This testing ensures that the hammer, trigger sear, and safety stays in place and nothing fails.

To test the fire control group, in particular, AMI Defense puts a live primer into the empty casing with the hammer cocked and safety on and drops the firearm in a variety of different ways – butt down, barrel down, on its side, on its top, and on its bottom. Then, the safety’s taken off and the drop testing is performed again.

“I want to make sure our product locks up and is as safe as possible, and so far, she’s shining,” Owens says.

Overall, he says recent advancements in technology allow AMI Defense to produce a higher-quality product from casting that may not have been possible in the past.

“With castings, you can get voids inside, underneath the metal, deep inside,” Owens says. “With those voids under stress, you can get cracks and breaks. That’s where castings have gotten a bad name in the past. With the advancements in technology – with the aerospace technology that’s out there that we use – we’ve either eliminated or extremely minimized that possibility. By doing the HIP-ing and using the aerospace technology that we have, we can alleviate or minimize that problem.”

Casting, he says, can now create end products as strong as those produced through forging, as long as the casting process is done correctly. In addition, products made from casting typically require less machining, which Owens says can lead to cost and labor savings.

“Forging is a block of metal they heat up, and then they’ll hit it with a press, and they just smash it into the shape, and then they’ll machine it out from there,” he says. “Ours is poured into the shape, and then we go from there. With what we’ve done and the techniques we use and the advancements out there, we’ve made an extremely strong and reliable frame. We’ve got guns that have had thousands of rounds through them with no problems whatsoever. The end result, a frame that you can trust your life with.”

AMI DEFENSE
https://www.amidefense.com

About the author: Melissa Schiller is senior editor with Defense and Munitions and can be reached at mschiller@gie.net.