View Full Version : Magpul UBR install guide and pictorial review

1 September 2007, 14:46
Weapon System: AR15/ M16

Manufacturer: Magpul (http://www.magpul.com)

Item Installed: UBR/ Utility/Battle Rifle Stock (http://www.magpul.com/catalog/index.php?main_page=product_info&cPath=70_72&products_id=187)

Purpose of Item: The Magpul Utility/Battle Rifle Stock is a replacement for carbine or rifle stocks, and gives an adjustable length of pull while maintaining a solid stock feel.

The Magpul Utility/Battle Rifle Stock is currently in preproduction status, so some information in this article may change as full production is gained.

The adjustability of a stock allows for a custom fit that will aid in sizing the weapon to the shooter. Stock lengths become important based off not only the body make up and physical attributes of the shooters, but with the equipment that they wear and use that they have for the weapon. Police Officers and Military troops who wear body armor understand that the extra bulk of their armor makes shooting a lot different, as do shooters who wear bulky clothing. What seems like a perfect fit in the comfort of your front room, isn't going to be the same thing as when you are going outside in -20 degree weather. In that same thought, the mission that your weapon serves may be something that changes on a regular basis. Riding and deploying from a vehicle with your weapon imparts a much different feeling than being out on a static range waiting to zero your weapon or shoot for fun.

The UBR- Utility/Battle Rifle Stock comes with a rubber buttpad, and Quick Disconnect (QD) mounting points in the front and rear of the stock.

Tools Needed: Allen Head Wrench
Screw driver (if taking off an fixed stock)
Stock Wrench

Items Included:
Magpul Utility/Battle Rifle Stock
Printed Instructions
unknown what else at this time

1 September 2007, 14:53
Before starting, basic weapon safety needs to be followed. Clear your weapon, and ensure there is no ammunition in the chamber, and no magazine inserted. I hate to bring it up in each writeup, but safety is something that canít be overlooked. All standard disclaimers apply here. This is an illustrated example of how I remove, install, and use items. If the use of basic tools is something you fear, find help before attempting any weapon work. Weapons are inherently dangerous, and so are tools if not used properly. While these steps work for me, it is not a magic answer for everyone. The use of the below steps still obligates the reader to accept responsibility for what they do.

With a safe weapon, push out your take down pins, and remove the upper from the lower. Next, we need to remove the stock. If you have a fixed stock (A1/ A2), take a look at the upper screw on the buttstock. This needs to be unscrewed and removed. After the screw is removed, the stock will pull off with direct pressure to the rear. When you remove the stock, there will be a spring and detent (spring shown in the below picture). The spring keeps pressure on the detent, so make sure you don't lose those pieces.


If you are removing a carbine receiver extension, use a stock wrench and loosen it applying pressure counter clockwise. Some companies, mainly RRA, use a threadlocker so heat may be an aid to removal. If your castle nut is staked, you will need to brace the lower receiver or grab a friend to help hold it down.


1 September 2007, 17:37
For rifles stocks, you should see the round receiver extension (buffer tube). Using a wrench, grab the end of the tube and turn counter clockwise to LOOSEN it. For right now, just loosen it.

If replacing a carbine tube, loosen the castle nut all the way, then remove the plate and watch out for the spring. Then twist the tube out of the receiver.


The reason we want to loosen the receiver extension, but not remove it is because there is yet another spring captured piece, but this one is under quite a bit of pressure and will fly out if not held in position with your fingers. Once you have used your wrench to loosen the receiver extension, hold your finger over the buffer retaining pin (shown below) and gently release it as you unscrew the receiver from the tube.


1 September 2007, 17:43
With the old receiver extension out, thread the Magpul UBR Entry length receiver extension into the receiver. Keep your finger down over the buffer retaining pin until it is recaptured. Now tighten down the end of the tube (clockwise) and get it nice and snug. Unlike a standard carbine stock, the UBR locks into the rear of the receiver, which prevents the stock from spinning.


1 September 2007, 18:03
With the receiver extension (buffer tube) securely in place, you should see a setup similar to the below picture. Take the UBR stock, and press it over the receiver extension. It will probably be a snug fit, so use a little pressure if needed. In the case of mine, it was snug, but not what I would call tight, but it was certainly more "fitted" than the A2 stock it was replacing.

Take care that when you are pressing the UBR into place that you don't squash the spring that is sticking out of the receiver.


In the below picture you can see the spring, and its worth pointing out that this spring needs to go into place without being deformed. Take a little care, and you shouldn't have any problems. You should also be able to see the portion of the UBR that interfaces with the cutout of the receiver. Press the stock in and this piece should push into place.


1 September 2007, 18:11
The next step is screwing the UBR into the receiver extension. The below picture shows the flat head allen screw next to the hole that it will go into.


Insert the screw, and tighten it down. If you want to apply some form of thread locker, now would be the time to use a small drop.


1 September 2007, 18:31
Congratulations, you have now installed your UBR, and you are ready to function test and test fire your weapon. However, there is a little more that the UBR offers.

The UBR uses two QD mounts to enable front or rear of the stock sling mounting. These QD mounts can be swapped to either side.

To remove the QD mount, insert an Allen wrench into the large side, and turn. There are Allen head screws on both sides, so if the screw spins freely without loosening, use an Allen wrench on the other side as well to lock it down.


Looking at the below picture, you can see a male and female side to the QD mounts.


Once you have them setup the way you want, use your Allen wrench(es) and tighten everything back down. It doesn't get much easier than this to configure a weapon for lefties.


1 September 2007, 18:54
Last, but certainly not least, here are a few pictures of the UBR installed on weapons. We are working on a complete review of the Magpul UBR, but it is still a ways off. Currently I've been running the UBR doing CQB style drills and clearing buildings, the UBR also needs to make its way to other instructors (I admit I've been a bit selfish with it). In the works is turning the UBR over to sniper instructors and getting feedback from their point of view.

For now, enjoy the pictures, and feel free to start a UBR thread in the discussion forums.