Magpul UBR Stock install on an AR-15 SBR for educational purposes

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For what I do with this AR (stationary shooting), this is the best of both worlds. I can have a consistent cheekweld and still adjust the length of pull for smaller shooters or for bulky winter clothing. There is no doubt that the UBR is well-built and will most likely outlast me. However, if I were building out a M4 style AR, this wouldn't be my first choice. It's just too heavy. Give Magpul some time and I bet they come up with a lighter version. This is design is just too cool to not get some R&D tweaking. The UBR is innovative in that it keeps the top portion of the stock fixed and the bottom portion adjusts to different lengths.

The way it is constructed gives you the strength of a fixed stock, with the adjustability of a collapsible stock. The Pre-production UBR's come with two different width tops which can be changed with the removal of four hex head screws. It utilizes an entry length buffer tube and carbine length buffer spring and buffer. The buffer and spring are not included so if you are moving from a rifle length system, you will need to order replacements. The lower portion of the stock contains a small compartment which can be utilized for storage of any number of different items. Not too terribly hard if you are the least bit mechanically inclined.

Start by clearing the weapon, then remove the upper from the lower. Remove the buffer and spring, set aside. Place the lower in a padded vise, be careful with the amount of torque you use. If your stock was a collapsible and had the castle nut staked, and it should have, you will need to get a punch and hammer and give the stakes a couple wacks to remove material. Then you can use your stock wrench to turn the nut loose. If you don't have a stock wrench and can't borrow one, I suppose a screw driver will work to loosen the nut.

At first glance the stock seems pretty basic. 7 positions, a storage compartment, and a release lever. However as you start to look closer you will notice this stock has several subtle features. One of the features I liked was the ability to remove the storage compartment. As a personal preference, I like having an open skeletonized stock. For those who are interested in using it, there is enough room for 123 batteries or an extra firing pin. I hope you enjoyed my Install video and review!