The Grayboe Core Rifle Stock and Universal Mini Chassis (UMC) Bundle combines an adjustable precision rifle stock with a modular aluminum chassis system. Designed for long-range shooting and competition, the Core provides a rigid, stable platform with adjustable ergonomics, while the UMC system allows multiple compatible rifles to share the same stock.
Choose between forged carbon fiber and forged fiberglass stock construction, then select the Universal Mini Chassis inlet that matches your rifle action. Each bundle includes one Grayboe Core stock and one action-specific UMC.
Grayboe Core Adjustable Rifle Stock
The Grayboe Core is a solid forged-composite rifle stock designed for precision shooting. Its substantial construction, vertical grip, adjustable cheek piece, and length-of-pull spacers provide a stable, configurable platform for different shooters, optics, and shooting positions.
The cheek piece adjusts vertically and horizontally for proper alignment behind the optic. A vertical grip with thumb shelf and slight palm swell supports consistent hand placement, while 1/4" length-of-pull spacers allow further adjustment.
Choose Your Core Stock Material
Forged Carbon Fiber
The premium Core configuration uses solid forged carbon fiber construction. Unlike traditional woven carbon fiber, forged carbon typically uses short carbon fibers distributed throughout a resin matrix and molded into a solid component. This produces a dense composite structure with a distinctive marbled carbon fiber appearance.
Grayboe developed the forged carbon Core with an emphasis on strength, rigidity, and durability. Its substantial construction is particularly suited to precision rifle applications where a heavier, stable shooting platform is preferred.
The forged carbon version weighs approximately 6 lbs. with the Universal Mini Chassis installed. This is the heavier of the two material options and is not intended as a lightweight alternative to fiberglass.
Forged Fiberglass
The forged fiberglass Core uses a solid fiberglass composite construction, providing the same stock geometry, adjustability, and UMC compatibility as the forged carbon version.
At approximately 4.5 lbs. with the UMC installed, the fiberglass Core weighs about 1.5 lbs. less than the forged carbon version. It provides a more economical material option while retaining the Core's precision-oriented features.
Core Stock Features & Specifications
- Solid forged carbon fiber or forged fiberglass construction, depending on selected configuration
- Compatible with Grayboe Universal Mini Chassis systems
- Adjustable cheek piece with vertical and horizontal adjustment
- Adjustable length of pull using 1/4" spacers, with a minimum length of 12.75"
- Vertical grip angle with thumb shelf and slight palm swell
- Grayboe Techno Gel recoil pad
- Full-length M-LOK mounting interface along the bottom of the forend
- Seven QD sling attachment inserts
- Compatible with Grayboe's optional aluminum two-round cartridge holder
- Universal barrel channel accommodating contours up to 1.250" straight barrels
- Forend tip barrel channel diameter: 1.330"
- Forend length: 12.25", measured from the face of a short-action Remington 700
- Right-hand stock configuration
Core Stock Weight Comparison
- Forged Carbon Fiber: Approximately 6 lbs. with UMC installed
- Forged Fiberglass: Approximately 4.5 lbs. with UMC installed
What Is the Grayboe Universal Mini Chassis?
The Grayboe Universal Mini Chassis (UMC) is a precision-machined aluminum bedding system that connects a rifle action to a compatible Grayboe stock.
Each UMC is machined internally for a specific rifle action, while the exterior maintains a standardized interface that fits Grayboe's UMC-compatible stocks.
This modular design allows different rifle platforms, action lengths, and calibers to use the same compatible stock, provided each rifle is paired with its own matching UMC.
One Stock, Multiple Compatible Rifles
The primary advantage of the UMC system is flexibility. Instead of purchasing and bedding a dedicated stock for every rifle, shooters can use one compatible Grayboe stock with multiple rifle actions.
Each rifle requires its own action-specific UMC. Once paired, the rifle and chassis can be moved together between compatible Grayboe stocks without changing the action-to-chassis bedding interface.
This allows shooters to use different rifle platforms in the same stock, or move an existing rifle and UMC assembly between compatible stock designs.
Mini Chassis vs. Traditional Rifle Bedding
Traditional glass bedding creates a fitted surface between a rifle action and stock. Its purpose is to establish consistent contact and support for the action.
The Grayboe UMC uses a rigid, precision-machined 6061-T6 aluminum bedding interface instead. This provides a consistent mechanical fit without requiring conventional glass bedding for supported rifle and stock combinations.
Because the action remains attached to its dedicated UMC, changing between compatible stocks does not require reestablishing the action-to-chassis bedding interface. Actual accuracy and zero retention depend on the complete rifle configuration and proper fitment.
Available Universal Mini Chassis Inlets
Brownells offers Grayboe UMC configurations for the following rifle actions:
- Remington 700 Short Action
- Remington 700 Long Action
- Howa 1500 Short Action
- Howa 1500 Long Action
- Tikka T3 Short Action
Important: Each UMC is designed for a specific rifle action and action length. The standardized stock interface does not mean the chassis itself is interchangeable between different rifle actions.
Verify your rifle's exact model, action length, and compatibility before selecting a UMC inlet. Aftermarket actions, triggers, and other components may have additional fitment requirements.
Available UMC-Compatible Grayboe Stocks
The same action-specific UMC can be used with different Grayboe stock models that feature the standardized UMC inlet. Brownells currently carries three compatible stock options:
- Grayboe Core: Adjustable precision rifle stock with configurable cheek height and length of pull.
- Grayboe Halo: Fixed rifle stock compatible with the Universal Mini Chassis system.
- Grayboe Flagstaff: Fixed rifle stock compatible with the Universal Mini Chassis system.
Additional compatible stocks can be used with an existing UMC without purchasing a new chassis, provided the stock supports the same standardized UMC interface.
AICS Magazine Compatibility
The Universal Mini Chassis incorporates an AICS-pattern detachable magazine interface, eliminating the need for separate bottom metal.
Magazine compatibility depends on the selected UMC inlet, cartridge, and magazine dimensions. Short-action and long-action configurations have different magazine requirements.
Tikka T3 Note: Grayboe specifies MDT polymer and MDT/Accurate Mag steel AICS magazines for its Tikka T3 UMC. Verify magazine compatibility for your selected rifle configuration.
Universal Mini Chassis Features & Specifications
- Material: Precision-machined 6061-T6 billet aluminum
- Weight: Approximately 14 oz.
- Finish: Type III hardcoat anodized or black Cerakote, depending on model
- Stock Interface: Standardized Grayboe Universal Mini Chassis inlet
- Rifle Interface: Action-specific inlet
- Magazine System: AICS-pattern detachable magazines
- Integrated magazine interface eliminates the need for separate bottom metal
- Optional adjustable magazine release available on applicable configurations
What's Included in This Bundle?
- One Grayboe Core rifle stock in the selected forged carbon fiber or forged fiberglass configuration
- One Grayboe Universal Mini Chassis matched to the selected rifle action
- Manufacturer-supplied UMC mounting hardware and action screws
Please Note: This bundle includes a rifle stock and Universal Mini Chassis only. Rifle, magazines, optics, and other accessories are not included.
Compatibility & Ordering Notes
- Select the UMC inlet that matches your exact rifle model and action length.
- Select your preferred Core stock material: forged carbon fiber or forged fiberglass.
- The Core UMC-compatible stock is offered in a right-hand configuration.
- Each additional rifle requires its own compatible Universal Mini Chassis.
- AICS magazine compatibility varies by rifle action and UMC configuration.
- Aftermarket actions, triggers, and other components may require additional compatibility verification.
