From Firing Pins to Precision Screws: Inside EPSP’s Legacy of Accuracy

What began as a wartime mission in 1943 has grown into a trusted source for precision screws and high-performance machined components. At Extreme Precision Screw Products (EPSP), our roots trace back to the manufacturing of .50-caliber firing pins during World War II, parts that demanded absolute reliability in combat.

That same standard of excellence continues today. From our beginnings on the battlefield to our current work in aerospace, defense, medical, and custom automotive sectors, EPSP has evolved into a leader in precision screw manufacturing. But while the machines have changed, our dedication to accuracy hasn’t wavered.

A WWII Foundation Built on Precision

EPSP was founded by twin brothers Harold and Howard Aseltine in Flint, Michigan, in the midst of World War II. Their first job? Manufacturing firing pins for the .50-cal Browning machine gun, a component that had to function flawlessly under the most extreme conditions.

Each pin had to meet strict military tolerances, making early quality control essential. Though EPSP’s facility was modest in those days, the team relied on craftsmanship, ingenuity, and discipline to produce components that lives depended on.

Those early days embedded something deeper into EPSP’s culture, a commitment to precision under pressure. It’s a philosophy that still drives the company, especially in the manufacture of today’s high-tolerance precision screws.

Expanding Beyond the Battlefield

After the war, EPSP could have faded away like many wartime suppliers. Instead, the Aseltines made a forward-thinking move. They shifted focus from weapons components to broader machining needs in an economy hungry for innovation.

EPSP began serving the automotive and tooling industries, gradually expanding its capabilities and customer base. As technology advanced, so did EPSP, investing in new equipment, expanding inspection systems, and refining the art of precision screw production.

This period marked a transformation. What started as a war-time shop evolved into a full-service precision machining company, capable of producing complex threaded parts, tight-tolerance components, and customized fasteners.

Precision Screws in Today’s High-Performance Applications

Today, EPSP operates out of a 16,000-square-foot facility, serving industries where failure isn’t an option. Our core specialty? Precision screws built for performance-critical environments.

These components are found in:

• Aircraft assemblies
• Surgical instruments
• Firearm chassis
• Military and defense systems
• Custom automotive builds

Each screw is produced to exact specifications using advanced CNC equipment and Swiss-type lathes. Whether the job calls for titanium, stainless steel, Inconel, or custom alloys, we deliver parts that meet or exceed industry standards.

It’s not just about threading metal, it’s about making sure every precision screw performs consistently under pressure, time after time.

What Makes EPSP Precision Screws Different?

Manufacturing precision screws is about the mindset. At EPSP, we bring decades of experience to every component. That legacy influences everything we do, from raw material selection to final inspection.

Our process includes:

• Tight-tolerance machining with multi-axis lathes
• In-house inspection with advanced metrology tools
• DFARS-compliant materials for defense and aerospace contracts
• Custom screw designs engineered for unique performance needs
• Prototype and production support for all stages of development

When we say precision screws, we mean more than just dimensionally accurate parts. We’re delivering peace of mind through consistent quality and repeatable results.

Bridging Heritage with High Technology

EPSP’s reputation for excellence doesn’t come from volume—it comes from precision. Our customers return because they trust our attention to detail, and because they know we don’t take shortcuts.

Inside our Flint facility, heritage meets high-tech:

• CNC machines run multi-op parts with sub-micron accuracy
• Experienced machinists hold tolerances within tenths
• Every precision screw is inspected with tools calibrated to aerospace standards

And beyond the shop floor, our customer support team offers technical guidance and responsive communication. Whether you’re ordering 500 screws or fine-tuning a prototype for medical use, you’ll have a partner who understands what’s at stake.

From the .50-Cal to the Final Thread

It’s easy to overlook something as small as a screw, but when the mission matters, every detail counts. At EPSP, we haven’t forgotten where we started. The .50-caliber firing pin wasn’t just a part, it was a promise. A promise that the equipment would work when lives depended on it.

That promise lives on today in every precision screw we ship. Whether it’s headed to a clean room or a cockpit, we build it with the same pride that guided us in 1943.

Why Choose EPSP for Precision Screws?

With over 80 years of manufacturing experience, EPSP offers our legacy. Our clients rely on us because they know:

• We don’t miss tolerances
• We don’t outsource quality
• We don’t treat small parts as afterthoughts

Your precision screws may be small, but they hold big responsibilities. And when they’re made by a company that’s been earning trust since World War II, that makes all the difference.

Need guidance on a specific project? We’re ready when you are. EPSP is built on trust, quality, and precision—and we’re here to help you succeed. Contact us