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XS Sights Armorers Block for AR Rifles in Review

Is this aluminum AR assembly block, the "Swiss Army knife of AR tools?"

XS Sights Armorers Block for AR Rifles in Review

A look at XS Sights’ Armorers Block for building AR rifles. Not only does it work for both uppers and lowers, it works for AR-15s, AR-10s and LR/SR-25s.

The XS Sight company of Fort Worth Texas is well-known for producing high quality, easy to use night sights and especially their “Big Dot" DXT2 line of sights. These sights allow for quick target acquisition with handguns, making for easy and well-placed shots under high stress situations. That said, did you know XS also produces specialty firearms tools? I didn't until recently, when I was introduced with an opportunity to test and evaluate their new, Generation 2 AR pattern armor’s block. When contacted by friend and mentor David Fortier about this tool, I quickly jumped at the opportunity, as I am a fan of anything "AR". I had my expectations, and while they are stringent, the end result was much to my liking.

Constructed from 6061 aluminum billet, the armors block from XS Sights is no lightweight, but it is lightyears ahead of the competition.

While I am the first person to always advocate the use and acquisition of all proper tools for any type of work or maintenance on a person’s firearm, I also understand those tools are an investment in and of themselves. While it is of the utmost importance to invest in the necessities, the majority of home assemblers will skip on "unnecessary" tools, which play no part in basic assembly.

Note the clean lines and lack of machining marks. This is the "magwell end" of the block, designed for lower receiver interface.

The majority of the time these tools are proprietary and serve a singular purpose. For years now, I have used the "DPMS Panther Claw" vice blocks for both large frame and small frame rifle work. While well made, these tools only served the one purpose. This meant separate upper assembly blocks would be required for more in-depth work, such as: lapping and squaring the upper receiver interface between barrel extension and upper, as well as shimming and/or conductive barrel fitting. Due to this, delrin or polymer constructed upper blocks are poor choices for this type of work, meaning a secondary, aluminum block is necessary. Products such as this didn't widely exist, which is where XS Sights answered the call.

Here’s a better view of the magwell interface. Note the machined areas where the magazine release meets with the armor’s block. Also note the varying holes for small and large frame upper receivers.

The XS Armorers Block can easily be called the "Swiss Army knife" of AR tools, as this one block serves so many roles, from upper assembly to lower assembly and even crosses into Armalite AR-10 pattern and DPMS/LR pattern receiver sets. This means this one block can take the place of more than four necessary, traditional AR pattern gunsmithing tools. The XS Armorers Block came well-packaged, well-protected and with simple, straightforward instructions for all uses. The block is constructed from 6061 aircraft grade aluminum billet, nicely machined and bead blasted for a uniform finish. As hard as I examined, I found no noted machining marks on the finished product; simply a smooth, uniform and visually pleasant "frosted" appearance.

The block locks in snug and firmly with the magazine release. The click is solid and audible. Note how accessible the lower receiver is for assembly, disassembly, service or parts swapping.

For the more in-depth home builder, AR Armorer or gunsmith, this AR builder’s block offers another unique option not typically found on other upper assembly tools. The designed interface allows the user to utilize an upper lapping tool free of obstruction. This is useful for me, as I can lap and square the upper receiver, from a solid interface, thus allowing for more uniform and precise fitment of the barrel. This eliminates the need for a secondary receiver vice, streamlining necessary tools, both saving space and money.

A side view of the lower function of the XS Sights AR armors block Gen. 2. This makes the lower easily accessible and work easier overall.

The XS block also works well for lower assembly. Slide it into the lower through the magazine well, allowing the magazine release to lock into the appropriate slot. This lockup is positive and sturdy, allowing the user to easily install every lower component, placing the work area at eye level. This is well-engineered, well-executed and works well for tedious work, such as: pivot pin installation, hammer installation and castle nut staking.

Note the interface between the block and the upper receiver. This allows the block to be used for far more than just assembly. Accurizing with the XS Sights Gen. 2 Armorers Block is easy, especially lapping uppers and conductive barrel fitting.

Before use, I would recommend lightly coating the ball bearings on the push pins with oil. This will make the initial use of the pins much easier, as they are stiff from the factory. While the interface with the lower receiver is overall solid, I personally don't feel comfortable applying the necessary torque to the castle nut, for final buffer tube installation. While only 40-foot pounds of torque is applied, the application of pressure is opposite of the block and lower interface (being in the magazine well). While I am sure it is absolutely safe to perform with no harm becoming of the lower receiver or tool, I still prefer to apply pressure directly at the source (by using a vice block tool for the buffer tube), instead of applying pressure across the receiver.

AR-15? AR-10? LR/SR-25? Big or small frame, the XS Sights’ Armorers Block will successfully work with all AR frame sizes on the market.

While good looking out of the packaging, that frosted finish doesn't stay picturesque long. I noticed several rubs while using it for the first time, especially when using the tabletop vice and when placing it into the lower. This does not deduct from the usefulness or quality in the least, and is expected of a tool with any use. I will also note, the aluminum to aluminum interaction will wear the finish on "less expensive" uppers and lowers. I was curious about this and placed a more budget oriented forged lower in and noticed small scratches on the finish. It is likely best to use this with receivers that have high quality anodizing jobs on them, as it can cause small blemishes (be it in inconspicuous areas) on budget parts.

A view inside an AR upper receiver, showing the unobstructed area in which upper receiver lapping tools will have to work. I personally use Brownells’ lapping tool and the fit is great.

The positives of XS Sight’s Armorers Block far outweigh the negatives and the negatives are nitpicking at best. This is a high-quality tool, well-engineered for years of service and offers the user several tools all rolled into one, and at one price tag. While offering the home builder a multi-tool, this would suit the AR armorer, gunsmith or even AR manufacturer far greater, simply due to its potential uses in terms of accurizing the rifle.

Overall, I think this is one of the most useful singular AR tools available, outside of an armorer’s wrench, for servicing and building the AR rifle. It is easy to use, easy to figure out, simplistic and fills so many roles that previously required 3 or more tools to complete, all at a very fair and reasonable $83.00 price tag. Normally I dislike "multi-tools" as sometimes their broad range of uses actually degrades the individual use, this is different, if anything this is the "Swiss Army knife" of AR builder’s tools.

If you have any thoughts or comments on this article, we’d love to hear them. Email us at

About the Author:

Michelle Hamilton has a Bachelor’s degree in Criminal Justice/Homeland Security, is a serious student of wound ballistics, military history, small arms design and manufacturing and is a competitive shooter.


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