Magpul UBR Utility/Battle Rifle Stock

The Magpul UBR (Utility / Battle Rifle), U.S. Patent 6651371, is a fully featured, adjustable butt stock for the AR15 / M16. Unlike typical collapsing stocks, this modular design offers the stability of a fixed stock with consistent cheek weld in any position.

Seven-position length-of-pull (LOP) adjustment is quickly executed with gross motor movement while the integral preset system allows direct access to a preferred position. A robust lock mechanism and multi-shell construction increase durability under severe impact conditions experienced during malfunction clearing and accommodates large-bore AR calibers.

The UBR also provides extra counterbalance weight to improve handling on full-length rifles and weapons with muzzle-heavy accessories or grenade launchers. Optional components such as dual-side sling mounts and metal strike plate allow the UBR to adapt to the mission at hand.

Note: The UBR includes the necessary Entry Receiver Extension tube and all mounting hardware. An M4 Carbine Buffer and Spring are required for use with the UBR and are not included.

Features:
Mounts on durable Entry Receiver Extension tube (Included)
7-Position LOP adjustability with customizable preset system for fast access to preferred length
Multi-shell construction provides solid foundation and shields critical operating parts from penetration damage
Solid "fixed stock" lockup in all positions
Enhanced lock mechanism w/ impact buffer increases drop strength and shock reduction
Repositionable cheek piece accommodates users requiring extra eye-relief
Stout construction provides counterbalance weight for improved weapon balance and handling

Sling Mounts
Front / Rear - Single-side push-button QD sling mounts (Left-Right Reversible)
Bottom - 1.25" Sling loop

Included Accessories:
Storage Module (Left-Right Reversible / Removable)
Rubber Butt-Pad, 0.30" (Removable)

Specifications:
UBR Stock (w/ Rubber Butt-Pad, 0.30")
Weight, w/ Entry Receiver Extension: 1.56 lb.
Length, Stock: 8.00-11.30 in.
LOP Adjustment: 7-Position (0.56 in. / position)
LOP Adjustment Range: 3.3 in.
LOP, Collapsed (M4/M16): 10.9 in.
LOP, Extended (M4/M16): 14.2 in.

This item or some of its components cannot be exported from the United States of America without a valid export permit from the U.S. State Dept. Unfortunately, this also includes APO addresses due to ITAR restrictions.

 

Magpul UBR Features & Construction

Stationary Cheek Piece – Cheek piece allows for consistent cheek weld for comfortable use of sights/optics and nose-to-charging handle (NTCH) shooting regardless of stock position.

Release Latch – Release latch for LOP Adjustment

Front QD Mount – Single-sided front quick-disconnect sling mount. Can be re-mounted on opposite side for left-handed shooters. Ambidextrous QD mounts optional.

Receiver Key – Interfaces with lower receiver keyway for easy installation and positive stock orientation.

Rear QD Mount – Single-sided rear quick-disconnect sling mount. Can be re-mounted on opposite side for left-handed shooters. Ambidextrous QD mounts optional.

Storage Door – Storage door can be switched to opposite side for left-handed shooters or removed altogether.

Rubber Butt Pad – 0.30” thick Rubber Butt Pad.

Garrison Sling Loop – Can be replaced with optional Aluminum Strike Plate.

Preset & Remove Buttons – Adjustable LOP reset system allows direct access to one of five presets for quick adjustment to a preferred position. Remove Button on opposite side allows Stock Body to be easily removed from Main Tube Assembly.

 

Magpul UBR Installation Instructions

Step 1: Remove Original Stock

WARNING: Before beginning, make sure the weapon is unloaded, the chamber is empty, and the safety engaged.

Remove Upper Receiver from the weapon. Depress Buffer Retaining Pin and remove the Buffer and Action Spring. Remove the original stock using care to prevent losing the Takedown Pin Spring and Detent. See Step 2 below.

Step 2: Remove Original Receiver Extension

Remove Receiver Extension (buffer tube) making sure to retain the Buffer Retaining Pin/Retaining Pin Spring and Takedown Pin Spring/Takedown Pin Detent.

Note: If you have an A1/A2 fixed stock using a rifle-length receiver extension, the buffer and spring must also be replaced in addition to the receiver extension. See Step 7 for more information.

Step 3: Mount Entry Receiver Extension

Make sure Buffer Retaining Pin and Retaining Pin Spring are correctly placed inside the Lower Receiver. Depress and hold the Buffer Retaining Pin while screwing Entry Receiver Extension into lower. Tighten with armorers wrench (5/8”) 35-39 ft-lb. torque per US Army TM 9-1005-319-23&P Unit and Direct Support Maintenance Manual.

Note: DO NOT use Loctite or other locking compounds on receiver extension threads.

Step 4: Remove Stock Body

Bypass all presets and open stock to the last position marked “6”. Firmly hold the Stock Body and simultaneously depress the Release Latch while pushing the Remove Button from the right. Pull the Stock Body off the Main Tube Assembly.

Step 5: Mount UBR Main Tube

Verify the Takedown Pin Spring and Detent are placed correctly in the Lower Receiver. Slide the UBR Main Tube Assembly over the Entry Receiver Extension. Take care to avoid damaging the exposed detent spring and make sure it does not bind when seating the Main Tube. If necessary, use a soft rubber mallet to seat fully. Install UBR Butt Cap Screw with a flathead screwdriver until hand tight.

DO NOT use any other screw to mount UBR as it may damage stock or affect weapon cycling.

Step 6: Attach UBR Stock Body

Pull back and hold the Release Latch on the UBR Stock Body. Align Stock Body with Main Tube Assembly and gently slide parts together until the Stock Body stops (travels forward about 2.75”). DO NOT FORCE PARTS TOGETHER. Let go of the Release Latch. Push Remove Button and slide Stock Body forward until it clicks into place. Release all controls. Pull back fully on Release Latch and push forward on Stock Body to collapse stock.

Step 7: Install Buffer and Spring

Install Carbine Buffer (standard, H, H2, etc.) and Carbine Action Spring.

Note: Rifle buffers and action springs (like those used in fixed A1/A2 stocks) DO NOT function with the UBR.

AR10/SR25 ONLY: The UBR may be used with most 7.62 NATO rifles but requires the use of a special AR10 Carbine Buffer and Action Spring. Please contact techsupport@magpul.com for more information.

Step 8: Verify Installation

Make sure all screws are tight. Avoid over-tightening screws as this can permanently damage the stock. Reassemble the weapon and perform final inspection and function check per US Army TM 9-1005-319-23&P Unit and Direct Support Maintenance Manual. If you experience any issues during installation visit the “Tech Resources” section at www.magpul.com for further information. Always test fire your weapon before using it in an operational environment.

 

Magpul UBR Usage Instructions

Extend/Collapse Stock

Fully depress the Release Latch and pull the stock rearward to extend or push stock forward to collapse. The stock will extend until it hits either a preset stop (factory set at position “P5”) or the back stop. Intermediate positions may be selected by partially depressing the Release latch and ratcheting the stock back to the desired position. Let go of the Release Latch and push Stock Body forward to properly seat the locking mechanism.

Bypass Preset

To bypass a Preset when extending the stock, pull stock rearward while simultaneously depressing the Release Latch and pushing the Preset Button located on the left side. All presets are automatically bypassed when collapsing the stock – simply use the Release Latch and collapse to desired position.

Detach Stock Body

To remove the stock, bypass all presets and open the stock to the last position marked “6.” Firmly hold the Stock Body and simultaneously press the Release Latch while pushing the Remove Button from the right. Pull the Stock Body off the Main Tube Assembly.

To reinstall Stock Body, simultaneously depress the Release Latch and Remove Button while sliding Stock Body back on to the Main Tube Assembly.

Cleaning & General Maintenance

See above for Stock Body detachment instructions.

Main Tube Assembly – clean inside rails and locking grooves using a nylon brush or rag. Wipe off any oil, CLP, or cleaning solvents as these may attract dust and grime.

Sliding Stock Body – use a nylon brush or rag to remove dust, dirt, or debris from inside the rails, grooves, and locking mechanism. Apply a light amount of oil to Lock pawls and Override, use graphite lubricant in dry, dusty environments.

 

Magpul UBR Customization Instructions

Storage Removal/Adjustment

The Storage Door and Cover may be swapped from left to right or removed completely to adjust for user preference. To reconfigure the storage door, use a 1/8” Hex Key to remove the 4 10-24x1/2” Button Head Screws.

Swap door and cover and reinstall screws. To remove the storage doors completely, replace the screws with the shorter 10-24x3/8” Button Head Screws (included).

Note: The UBR requires the installation of all four screws for correct operation. Do not reinstall 10-24x1/2” screws without storage door and cover installed.

 

QD Removal/Installation

Remove Front Mount: using a 1/8” Hex Key and 5/16” Hex Socket remove 10-24 x 5/8” Button head Screw, Hex Nut, and Washer.

Use ¼” Pin Punch to remove QD Mount Cup.

If desired, install it on right side of Receiver Key in opposite manner. For complete removal substitute spare washer in place of QD Mount and reinstall original washer, screw, and nut. NEVER REMOVE THE RECEIVER KEY!

Remove Rear Mount: Remove 10-24 x 5/8” Button Head Screw and Hex Nut. Carefully use a Push-Button QD Sling Swivel to pull out the rear QD Mount Cup. Reinstall screw and nut or install cup on right side of stock in opposite manner. DO NOT USE WASHER IN REAR HOLE AS THEY WILL BECOME JAMMED INTO POLYMER.

 

Rubber Butt Pad Removal

The 0.30” Rubber Butt Pad is held in place by two screws and two polymer snap hooks (one on each side). To remove or replace the pad, first use a 1/8” Hex Key to remove two 10-24 x 5/8” Button Head Screws.

Next, use two small screwdrivers or bullet tips to push snap hooks inward. This will release the pad for removal.

For use without the Butt Pad, a checkered Butt Cap is available to fill the void located above the screw hole.

Preset Adjustment

Remove Stock Body to reveal Preset Locations on the bottom side of the Main Tube Assembly. Install Preset Screw (5-40 x ¼” socket head cap screw) in one of the positions marked “P1” to “P5” to adjust the favored position. The spare preset screw can be used to set a second preset position or as a replacement for a lost preset screw.