Gun Drilling: Process, Tools & Parameters

Gun drilling is a precision deep hole drilling process that uses a single-lip carbide cutting tool with internal coolant delivery and a V-shaped external flute for chip evacuation. Originally developed over 100 years ago for manufacturing gun barrels, it produces holes with exceptionally high depth-to-diameter ratios up to 300:1 in a single pass. Gun drilling achieves diameter tolerances of ±0.013–0.025 mm (IT6–IT9) and surface finish of Ra 0.4–0.8 µm as-drilled, often eliminating the need for secondary operations. The process covers diameters from 0.5 mm to 50 mm and is used across aerospace, automotive, medical, oil and gas, and mold making industries. Key components include the single-lip cutting edge, guide pads for self-piloting, internal coolant delivery at 50–200 bar, and high-pressure coolant systems with 10–20 micron filtration. For shops without a high-pressure system, see gun drilling without high-pressure coolant. For small-diameter work down to 0.5 mm, see micro gun drilling 0.5–2 mm. For rotating the workpiece against the drill to reduce whip in long bars, see counter-rotation in gun drilling. For tooling decisions, see the carbide gun drill bits buying guide.

How Gun Drilling Works

Gun drilling uses a tool with a single cutting edge and a hollow shank. High-pressure coolant is pumped through the internal channel and exits at the cutting tip, cooling the cut zone and flushing chips back along the tool’s external V-groove. Carbide guide pads immediately behind the cutting edge bear against the freshly machined bore wall, providing continuous self-piloting that keeps the drill on-axis to within 0.001 in/ft (0.08 mm per 300 mm). The result is a straight, accurately sized hole produced in a single continuous pass — no pecking, no reaming, no honing.

Key Capabilities

Gun Drilling Core Topics

• What is gun drilling? — definition, advantages, and when to use it → What is Gun Drilling
• How it works, step by step → How Gun Drilling Works
• Speeds, feeds, and parameters by material and diameter → Gun Drilling Speeds & Feeds
• Gun drilling machines — dedicated, integrated, and retrofitted → Gun Drilling Machines
• Applications across aerospace, automotive, medical, and more → Gun Drilling Applications
• Choosing a gun drilling service provider → How to Choose a Gun Drilling Service Provider
• Gun drilling vs BTA vs ejector — method comparison → Gun vs BTA vs Ejector
• Troubleshooting — chip evacuation, tool breakage, vibration → Gun Drilling Problems & Solutions

Gun Drilling in the Industry

Gun drilling is the default process for precision, deep, small-diameter holes in critical components. In aerospace it machines landing gear shafts and turbine cooling holes; in automotive it drills fuel injector bodies, common rail passages, and camshafts; in medical it produces cannulated bone screws and implants; and in oil and gas it makes downhole tools and valve bodies. Because the process delivers finished-quality holes in a single pass, it often eliminates reaming, honing, and their associated cost and handling time.

Start Here

New to gun drilling? Begin with the complete guide to gun drilling, or jump straight to the step-by-step process overview. To decide whether gun drilling fits your part, compare it with the other deep hole drilling methods.