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Black Rifle Disease Engineerin
Mk4 Drilling Jig For Bcm And Vltor Gas Blocks
Our editorial team reviews specifications, product data, and field-use information to keep pages accurate.
$75.00
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SKU: 430108872
Overview
Designed for BCM and Vltor specific gas blocks, this fixed jig provides a dedicated setup for drilling and pinning work on compatible barrels. It mounts through the gas block set screw holes with the provided longer set screws, and the guide hole is positioned on the barrel’s outside diameter to support a 50% pin diameter in the barrel. The jig is fabricated from carbon steel and is drilled to mount the barrel at a 1" center. It includes the needed set screws, nuts, and one #31 HSS drill, making it a focused tool for builders working with the specified gas block pattern.
Why Hunters Choose the Black Rifle Disease Engineerin
Bcm Vltor
Gas blocks
Carbon Steel
Construction for a rigid fixed
Mounts Through
Included longer set screws
Drilling Guide
Hole is positioned on the
Includes Needed
Set screws, nuts, and one
Key Features
- Fits BCM and Vltor specific gas blocks
- Fabricated from carbon steel
- Mounts to gas block set screw holes with provided longer set screws
- Drilling guide hole is located on the barrel OD
- Stock drilling hole size is #31 (0.120")
- Includes needed set screws, nuts, and one #31 HSS drill
Best Used For
- For BCM or Vltor gas block setups needing a dedicated drilling jig.
- For users mounting a barrel at a 1-inch center with the included guide.
- For builders who want the supplied #31 HSS drill and hardware included.
- For shop work centered on set-screw gas blocks with a fixed jig design.
Specifications
| Barrel Mount Center | 1" center |
|---|---|
| Compatible Gas Blocks | BCM and Vltor specific gas blocks |
| Drilling Guide Hole Location | OD of the barrel |
| Included Accessories | needed set screws and nuts and one #31 HSS drill |
| Material | carbon steel |
| Mounting Method | mounts to the gas block set screw holes using longer provided set screws |
| Pin Diameter In Barrel | 50% |
| Stock Drilling Hole Size | #31 (0.120") |
Pros
- Designed specifically for BCM and Vltor gas blocks
- Carbon steel construction for a rigid fixed jig
- Mounts through gas block set screw holes with included longer set screws
- Drilling guide hole is positioned on the barrel OD
- Includes needed set screws, nuts, and one #31 HSS drill
- Drilled to mount the barrel at a 1-inch center
Considerations & Trade-offs
- This jig is built for BCM and Vltor specific gas blocks, so it is not a universal fit for other gas block patterns.
- The drilling guide is set up for a #31 (0.120") hole and the included drill bit, which leaves little flexibility if a different pin size or setup is needed.
- The guide hole is positioned on the OD of the barrel to provide 50% pin diameter in the barrel, so the installation approach is specific rather than adjustable.
- The jig mounts through the gas block set screw holes using the provided longer set screws, so the setup depends on those attachment points being available and compatible.
Suggested Comparisons
- Gas block installation jig
- Barrel drilling jig
- AR-15 armorer tool
- Firearm maintenance and gunsmithing tools
Suggested Accessories
- Drill bits
- Set screws
- Nuts and fasteners
- Gun vise
Frequently Asked Questions
Which gas blocks is this MK4 jig made for?
This MK4 fixed jig is made for BCM and Vltor specific gas blocks.
What does the jig mount to on the gas block?
It mounts to the gas block set screw holes using the longer provided set screws.
What drill size does this jig use?
The stock drilling hole size is #31 (0.120"), and the jig includes one #31 HSS drill.
What comes included with the jig?
The product includes the needed set screws, nuts, and one #31 HSS drill.
What material is the jig made from?
The jig is fabricated from carbon steel.