Home Product Reviews B5 Systems: The Army Selected Stock for the M110 Rifle with NSN By: Steph Martz

B5 Systems: The Army Selected Stock for the M110 Rifle with NSN By: Steph Martz

B5 Systems: The Army Selected Stock for the M110 Rifle with NSN   By: Steph Martz

We all know the response we will get when asking for more gear in the military: “Okay, but does it have an NSN?”

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Womp womp…

Three words. National Stock Number

Gear and equipment acquisition within the Army is always tough when you have to do a separate purchase on either a government credit card or find a loophole in a different system to make the purchase. NSNs just make life easier for the unit and supply ordering. When it comes to the Sniper Sections within the Army they have to fight this battle all of the time, as a lot of good equipment still doesn’t have an NSN due to the lengthy process, and—I may be biased here—the lack of care to the sniper sections.

The latest addition to this small list of NSNs for our snipers though? The B5 Precision Stock: NSN 1005-01-701-3527

showing b5 systems ad for the new army approved stock including nsn
The Army has now given the B5 Precision Stock a NSN which will ease the process of ordering the stock for sniper sections. An adjustable stock, both in the cheek and length of pull, is needed to make “one shot one kill.” (Photo: B5Systems)

What is it?

The B5 Precision Stock is an adjustable stock in both the cheekpiece and buttpad that fits on mil-spec receiver extensions. The stock gives us “internal tensioners, ambidextrous fixed and quick disconnect sling mounts, gross length of pull adjustment via pull down with lockout, underside M-LOK accessory mount, and color-matched hardware.”

In simple terms, whether your gun is 5.56 or 7.62 and you’re trying to go out to distance, you no longer have to settle with a non-adjustable stock.

Why do sniper sections need it?

The Army Sniper sections specifically had a very large need for this stock. The Knights Armament M110 Sniper Rifle is issued with a non-adjustable, fixed buttstock—think old-school M16 triangle stock. This stock gives no help to the user.

When it comes to long-range shots everything needs to be right. Where the eye sits behind the scope impacts clarity and relaxation in facial structure, and where the shoulder sits on the stock affects arm strain and a straight, to-the-rear trigger press.

Until now, the snipers did not have the option to adjust the gun to make these things right. So what did they do? DIY fixes, of course. Throughout the Army, snipers started to add their own makeshift cheek pieces out of either tape or tape and foam. In turn, this gave them at least some relief in head positioning. However, it permanently damaged the stock when removing it and wasn’t easy to adjust if the gun was given to another shooter later (everyone’s bodies are different). This DIY fix is still on guns today and probably will be until/if the M110 is phased out. With an NSN adjustable stock now in the mix though? There is hope.

an army soldier firing the m110 with the traditional stock and diy cheek pad
Without a collapsible stock on the M110 units are finding DIY ways to adjust the cheek piece. This includes taping a pad of sorts to the stock for the added height. Notice that the length of pull cannot be adjusted with the traditional issued stock either. (Photo: ArmyTimes)

How do I convince my unit to purchase?

About two years ago I wrote a white paper for my state to purchase the B5 precision stock. This was before it ever had an NSN which made things a bit more complicated. Within the white paper, I touched on real reasons as to how it will benefit sniper sections. A portion of the paper read as…

” Background: The M110 SASS also has an outdated buttstock and scope mounting system. The current buttstock only allows customization for length of pull. To customize cheek height most snipers will tape a foam pad to the stock which is not adjustable and damages the stock. ..”

“Discussion: The B5 Systems Precision Carbine Stock Buttstock allows any sniper to be able to adjust length of pull and cheek comb height. This enhances the snipers ability to more accurately engage the target by providing a comfortable position. This stock also has enhanced durability due to no additional modification from the sniper needed. “

I also included the cost and looked at how many M110’s in the state need to be outfitted. Doing this homework will help push it. If you are on active duty, focus on unit size.

the nsn list for the advanced sniper accessory kit
Above are the items included in the Army Sniper Accessory Kit (ASAK). The B5 systems stock and extension are now included in this kit but this slide just doesn’t show it. This has since been updated. (Photo: CR2Solutions)

Now that this stock is listed within the Advanced Sniper Accessory Kit it is much easier to do the convincing since it now has an NON and is no longer considered “risky.”

Insider Tip: If your unit is coming up on a deployment they now have more money to purchase equipment, focus on pushing it during that time. Also, another good time is at the end of fiscal years when money needs to be spent.

What exactly does my unit need to purchase?

This question depends on the configuration that your unit is currently running. Usually, sections are running their M110s in two different conversions, which will decide what parts need to be ordered. If a receiver extension needs to be ordered your small arms repairer will need to install it. If the extension does not need to be ordered, a simple installation of the buttstock from the unit-level armorer should suffice, if the unit is okay with that.

Conversion 1 — From the Factory

This M110 version is straight from the factory. Most DoD units are still running the traditional M110 and have not changed anything about the rear stock, so they will need to order both a receiver extension and a precision buttstock to add the B5 Precision stock to the unit.

all pieces needed for the kac receiver extension kit including the receiver extension, buffer spring, buffer, end plate, and nut
Above is the receiver extension kit that will be needed if converting the M110 from the traditional buttstock to the adjustable. This kit is included within the B5 systems precision stock NSN. From Top and left to bottom right: Receiver extension, recoil spring, buffer, end plate, nut. (Photo: B5Systems)

Conversion 2, Sop Mod Buttstock

Many specialized units are now running this version of the M110. In this version, the receiver extension has already been replaced and the unit threw on a Sop Mod stock on the extension. To install the B5 precision stock, simply remove the Sop Mod and install the Precision Stock.

How To Order

According to B5 Systems, units can order in a couple of different ways. Some units buy the entire assembly straight from B5 Systems, this includes the receiver extension kit and the stock. Some units purchase off the commercial shelf and some purchase through TLS. When ordering with the NSN 1005-01-701-3527 know that it will come with both the stock and the receiver extension kit.

multiple m110s that are now kitted out with the badger optic mount and b5 systems stock
The M110s are kitted out with both the Badger Ordnance C1 Modular Mount and the B5 Precision Buttstock. These pieces of equipment both now have an NSN and are listed in the Advanced Sniper Accessory Kit. (Photo: CR2Solutions)

Features and Specs

The Army Approved version of this stock is the Medium Length FDE Version. On the commercial side, it comes in three lengths, short, medium, and long cheek pieces. These lengths are there to ensure that if mounted on an AR-15 or AR-10 platform the gun can still be charged even with the stock fully collapsed. It also comes in 5 colors.

a shooter using the b5 systems precision stock to take a long range shot
Cheek weld adjustability and length of pull adjustability are crucial for good shots and high-magnified scopes. Anything to help you keep a comfortable position on the gun will keep you successful. (Photo: CR2 Solutions)


  • Adjustable cheek weld and buttpad with precision dials.
  • Mounting slots for Accessory Cheekpiece.
  • 12 internal tensioners.
  • Color-matched machined hardware.
  • Fixed sling mounts.
  • Steel anti-rotational QD mounts.
  • No slip-cushioned buttpad.
  • Gross adjustment pull-down lever with lockout feature.
  • Underside M-LOK accessory attachment.
  • Made of Milspec materials and finishes.
  • Fits Milspec carbine receiver extensions (M4/a5/M110K).
  • Available in all standard colors.


  • Weight 20.65 oz.
  • Length 8.5 in.
  • Width 2.00 in.
  • Height 4.35 in.