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Weaver 8-40 Sight Screw Counterbore
Our editorial team reviews specifications, product data, and field-use information to keep pages accurate.
$45.99
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SKU: 080671840
Overview
Built for sight installation and repair work, this counterbore is intended for use with popular sight screws and sight base screws made to the listed specification. It features a high-speed steel construction and a 45-degree shoulder, with dimensions provided for the body, pilot, and pilot length to support precise setup. The tool calls for a No. 19 drill for the pilot hole, making it a practical bench item for gunsmithing tasks where a clean, controlled fit matters.
Why Hunters Choose the Brownells
High-speed Steel
Construction suited for sight screw
Made Exact
Specifications for most sight base
Sized Popular
Sight screws and sight base
Includes Clear
Pilot dimensions for straightforward setup
45-degree Shoulder
Design is specified in the
Key Features
- High-speed steel construction.
- Designed for popular sight screws.
- Made to exact specifications for most sight base screws.
- Overall 2 1/2 inches with 45-degree shoulder.
- Pilot diameter .165 inches and pilot length 1/8 inch.
- Use Drill No. 19 for the pilot hole.
Best Used For
- Gunsmiths installing or adjusting popular sight screws on compatible sight bases
- Users needing a counterbore tool made to exact spec for most sight base screws
- Shop work requiring a high-speed steel tool with a 45-degree shoulder
- Builders or maintainers drilling pilot holes with Drill No. 19 for sight screw work
Specifications
| Body Diameter | .250 in (6.3 mm) |
|---|---|
| Compatibility | Popular sight screws; most sight base screws |
| Material | High-Speed Steel |
| Overall Length | 2A 1/2 in (6.3 mm) |
| Pilot Diameter | .165 in (4.2 mm) |
| Pilot Length | 1/8 in (3.2 mm) |
| Recommended Drill Size | No. 19 |
| Shoulder Angle | 45 deg |
Pros
- High-speed steel construction suited for sight screw work
- Made to exact specifications for most sight base screws
- Sized for popular sight screws and sight base applications
- Includes clear pilot dimensions for straightforward setup
- 45-degree shoulder design is specified in the product data
Considerations & Trade-offs
- Designed for sight-base screw work, so it is a specialized tool rather than a general-purpose counterbore.
- Requires a No. 19 drill for the pilot hole, so setup depends on having the correct drill size on hand.
- The listed dimensions are specific to this tool, which means fit is tied to the stated screw and hole requirements.
- Made to Brownells' exact spec for most sight base screws, so compatibility should be checked against the intended application before use.
Suggested Comparisons
- Sight screw installation tools
- Counterbore tools for firearm work
- Gunsmithing drill and tap accessories
- Firearm sight base hardware
Suggested Accessories
- Drill bits
- Sight installation tools
- Gun vise
- Bench block
Frequently Asked Questions
What is the Weaver 8-40 Sight Screw Counterbore used for?
It is a high-speed steel counterbore made for popular sight screws and made to the stated spec for most sight base screws.
What size and dimensions are listed for this tool?
The listed dimensions are overall 2A 1/2" (6.3mm), body diameter .250" (6.3mm), pilot diameter .165" (4.2mm), pilot length 1/8" (3.2mm), and a 45-degree shoulder.
What drill bit should be used for the pilot hole?
The product data specifies Drill No. 19 for the pilot hole.
Is this counterbore intended for all sight screws?
The description says it is for popular sight screws and made to the exact spec for most sight base screws, but it does not claim compatibility with every sight screw.
What material is the tool made from?
The short description states that it is made from high-speed steel.