Why Is a Spiral Point Tap Also Called a "Gun Tap"?
If you’ve been in machining for any length of time, you’ve probably heard the term "gun tap" thrown around. But here’s the thing: not everyone agrees on what it actually means. In the U.S., "gun tap" almost always refers to a spiral point tap—the one with straight flutes and a chamfered tip that pushes chips ahead of the cutting action. In Europe and Asia, the same tool is simply called a spiral point tap, while "gun tap" might refer to a spiral flute tap used for blind holes.So why the name? And which one should you be quoting to your customers?
The "Gun Barrel" Origin Story
The most widely accepted explanation traces back to the 19th-century firearms industry. Gunsmiths needed to thread deep, straight-through holes in rifle barrels and other gun components—almost always through-holes. Standard hand taps produced long, stringy chips that wrapped around the tool, jammed thethe flutes, and ruined the thread finish.
To solve this, toolmakers designed a tap with a straight flute but a spiral (angular) cutting face at the chamfer. This geometry acted like a ramp, for cing chips forward—ahead of the tap and out the bottom of the hole. No more chip packing, no more reaming-style rubbing. The result was a cleaner thread, faster cycle times, and dramatically longer tool life.
Because the tool was develo0ped specifically for gun barrel production, it became known as the gun tap. The name stuck, even as the design spread to automotive, hydraulic, and general machining applications.
What a Gun Tap (Spiral Point) Actually Does
The defining feature is the spiral point—a cutting edge ground at an angle (typically 10°–20°) that ejects chips axially forward. This makes it the ideal choice for through-holes. The chips don’t accumulate in the flutes; they’re pushed clear of the cutting zone, so the tap keeps cutting cleanly.
Key advantages:Fast chip evacuation in through-holes
- Lower torque than spiral flute taps (less rubbing)
- Excellent surface finish on the thread
- High-speed capability on CNC machines
Gun Tap vs. Spiral Flute Tap — Don’t Mix Them Up
Feature | Gun Tap (Spiral Point) | Spiral Flute Tap |
|---|---|---|
Best for | Through-holes | Blind holes |
Chip direction | Forward (out the bottom) | Backward (up and out) |
Flute style | Straight flutes, spiral point | Helical flutes (30°–45°) |
Torque | Lower | Higherr |
Blind hole use | ❌ Chips pile at bottom | ✅ |
Real-World Example
A customer machining hydraulic valve bodies in 4140 steel was using spiral flute taps on through-holes. They suffered frequent chip packing and tool breakage. We recommended switching to a gun tap (spiral point) in M12 × 1.75 HSS-E with TiCN coating. Chip evacuation improved immediately, tap life increased from 400 to 1,800 holes, and cycle time dropped by 18% thanks to lower torque and higher allowable RPM.
If your customer is threading through-holes in steel, stainless, or aluminum, a gun tap (spiral point) is usually the most cost-effective choice. It’s faster, lasts longer, and produces better threads than a spiral flute tap in the same application. Just make sure they’re not using it in a blind hole—that’s where chips have nowhere to go and the tap will bind.
Need help selecting the right tap geometry for your application? Send us your thread spec and material—we’ll recommend the optimal tool and coating for your production run.