MBA-3 Carbine Buttstock

(9 customer reviews)


The Luth-AR Modular Buttstock Assembly (MBA) for AR style carbines is designed to replace the standard buttstock on your AR. The MBA-3 is designed to work with a 6-position Mil-Spec or Commercial buffer tube. The MBA-3 features a 3-Axis Buttplate with Length-of-Pull adjustment as well as height and lateral adjustments, and an adjustable cheek rise in a low-cost, lightweight, strong and high-quality design.

The MBA-3 requires a Carbine buffer tube, either Mil-Spec or Commercial. Please review the information provided in the Requirements tab. This stock works with both carbine Commercial and Mil-Spec tubes/assemblies.

The MBA-3 also features an anti-rattle set screw. The modular design of the MBA Buttstock allows you to configure your buttstock to your specific and personal needs. Includes a rail attachment for attaching a monopod. The MBA features multiple attachment points for a sling, including molded pockets that will accept Grovtec QD cups, sold separately.  Available in Black or Flat Dark Earth, or Freedom Flag Cheek Rest (Black only).


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  • Fully Adjustable Carbine Buttstock assembly to mount to a carbine rifle (6-positions mil-spec or commercial tube) – This is our carbine stock
  • The MBA-3 requires a Carbine buffer tube, either Mil-Spec or Commercial. Please review the information provided in the Requirements tab. This stock works with both carbine Commercial and Mil-Spec tubes/assemblies.
  • Additional 1″ height on cheek rest
  • 3-axis Adjustable Butt Plate Assembly extends additional 1 1/16″ length of pull and includes the following movement:
    1. Horizontal for linear adjustment (i.e. length of pull)
    2. Vertical for a perfect butt plate fit into the curvature of the shoulder.
    3. Lateral adjustment for a ½ inch left or right cast
    4. This butt plate assembly is interchangeable with the original MBA-1 Buttstock
  • Includes a Picatinny Rail on the bottom rear of the Stock Body to attach your choice of many accessories.
  • Designed a flat bottom index set screw (10-24) to eliminate that constant rattle of carbine collapsible buttstock. This also allows you to secure the stock in your favorite position.
  • The MBA-3 comes with a  medium soft rubber recoil pad, Duro 85.
  • The Luth-AR MBA-3 weighs roughly half that of comparable stocks coming in at just 18.5 ounces.
  • Fits all .223 and .308 AR carbine style rifles
  • Super Strong Glass Filled Nylon
  • Easy to replace and quick to install
  • Uses 4 out of the 6 positions on a mil-spec or commercial tube
  • If you require a butt stock that will utilize the first 2 holes of the buffer tube to fully collapse, you can remove the cheek rest from the MBA-3, or order an MBA-4, order an MBA-4 and a 3-axis buttplate or order an MBA-5 buttstock.


  • Ergonomic
  • Adapts To Existing Commercial and Mil-Spec Buffer Tubes
  • Certain after Market Commercial Buffer Tubes that exceed  1.172″ diameter, may not fit
  • The MBA-3 and MBA-4 are available in Black or Flat Dark Earth
  • The vertical struts for the MBA-3 are fixed, therefore the cheek piece is not reversible like the MBA-1 however the cheek piece itself is designed with a cheek pad for left-handed use
  • Caution: the MBA-3 and MBA-4 Carbine buttstocks are not designed to be used with Large Bore Calibers such as .338 Lapua or .50 BMG applications. See our MBA-1 and MBA-2 Rifle buttstocks as alternatives.
  • The MBA-3 Carbine buttstock is NOT interchangeable with A2 standard buffer tube. You will need to purchase a MBA-1 or MBA-2 Rifle buttstock to fit A2 tubes 

Compatible Buffer Assemblies:

  • .223 Mil-Spec Carbine Buffer Assembly
  • .223 Commercial Carbine Buffer Assembly
  • .308 Mil-Spec Carbine Buffer Assembly
  • .308 Commercial Carbine Buffer Assembly

Additional Information

The MBA-3 does not include the following accessories, they can be purchased on our website separately in the Accessories section:

  • Sling Swivels (Side or Rear) Sold Separately, see below. Also see Tech-Tip Videos
  • Carbine Buffer tube
  • Carbine Buffer Body
  • Carbine Buffer Spring
  • Latch Plate
  • Lock Ring

Installation Notes:  

  • When used with the smaller diameter Mil-Spec tube you can adjust the set screw located on the left hand side using the included 3/32” Allen wrench. Turn clockwise to slowly tighten the set screw until it contacts the buffer tube. The Anti-rattle set screw is NOT designed to lock the position of the stock. Over tightening may damage the butt stock.
  • When sliding the buttstock onto a 6-position buffer tube, the lock pin has a notch in the head of the lock pin that must line up with a tab on the stock body. Once the slot and tab are lined up, the pin can be fully retracted allowing the buttstock to slide onto the tube. The MBA-3 should slide easily without resistance. If there is any resistance, the lock pin is not fully retracted. 
Luth-AR Note on Savage Rifles:
Our MBA-3 is designed to fit standard Mil-Spec and Commercial Tubes. Some Savage tubes have been found to be oversized making our stock fit very tightly. Please note that you may need to simply purchase a standard carbine tube in order for this to pair correctly. Note: Customers have reported that the MBA-3 or MBA-4 fit the buffer tube that comes on the new model 110 BA Stealth. If you have the older model 110 BA you may have to simply change the buffer tube.
SKU: MBA-3B — Black

SKU: MBA-3F — Flat Dark earth

SKU: MBA-3FF — Freedom Flag

Additional information

Buttstock Type





.223, .308

Buttstock Weight

19.2 oz

Extended Length of Pull

15 5/8"

Collapsed Length of Pull

11 11/16"

Overall Extended Length

8 3/4"

Overall Collapsed Length

7 11/16"

Cheek Rise

1" Fully Extended

Additional Length-of-Pull

1 1/16″

Available Colors

Freedom Flag, Black, Flat Dark Earth

9 reviews for MBA-3 Carbine Buttstock

  1. carterlillian12

    I have many friends that own the Magpul PRS stock, they like it but have multiple complaints about it. Its heavy, doesn’t hold settings, needs a special buffer tube, oh AND THE PRICE! So after some research I found Luth-AR, and better yet the MBA-3!! This stock is by far the better between the two! Now all my AR buddy’s want to ditch Magpul and go with the MBA-3. I will be using these stocks on all of my AR builds from here on out.

  2. OldArmyVet

    This is a great Stock, having used various forms of the M16/AR15 and it’s derivatives, this is a great piece of gear. It’s quality for the price can not be beaten. The fit and finish are great (on a mil. spec buffer tube). The fit and finish is really nice, the action of all the subcomponents is great too. I do not feel like this will become worn out. The action is also better than the standard issue M4 adjustable stock. I would recommend this product, and qould have been glad to have it while deployed. If I could add one thing, it would be a rubber / silicone insert for the buttpad to better maintain thw rifle in your shoulder pocket.

  3. HMFIC03

    Don’t even bother trying to find a better stock – there isn’t one. Infinite adjustments and a side receiver extension tension screw take out all rattle. I have three MBA-1’s and my wife has this MBA 4 and now I want one for myself. Magpul sling swivel cups fits nice and snug in these for QD slings. Only complaint i have is, it is not offered in tan yet Luke and Ash

  4. n3480h

    Outstanding! Finished my 300 Blackout build with the new MBA-3F this week and it’s racking up compliments on its appearance and functionality. This is our third Luth stock and we love them all. The color was a very close match to the Cerakote FDE that I applied with an airbrush. Another winner from Randy and the gang at Luth.

  5. hedrick.larry

    Pros: Before I begin, I am going to start with Luth-AR’s customer service 5 stars. They are prompt to reply and work with you. They went so far as to recommend a distributor in my area once shipping was cost prohibitive. It is getting rarer and rarer these days to find that level of service. Alright the product MBA-3F. I normally do a ton of research including hands on before I buy any product. This does take some time but analyze twice, spend once is something I try to reason with. I took a gamble on this product as it is so new there is nothing on the market like it. The gamble paid off. This is an amazing product! Fit and finish is great! Installation was intuitive and simple even though Luth-AR took the time so have the installation instructions printed inside the box so that even a person with zero knowledge would know what to do. Took under 30 seconds to install. The lock setting to remove the “rattle” works perfect. No issues with my buffer tube at all. Everything on this stock works as advertised. Alright now is the part for my opinion on things that could be improved. But these are such slight things that I really had to nit-pick them.

    Cons: The butt pad. I had a VLTOR EMOD before I switched and I got used to a squishy rubber butt pad only to find that the luth-AR was hard plastic. Not a big problem just expectation management. Next QD swivel slots. The MBA-3F comes with per-selected QD holes but you have to buy the additional QD inserts from Luth-AR’s accessories section. Small thing but this drives me insane when it is something that could have been built in or added when you purchase the entire assembly. Because I use QD swivels for my sling I will have to buy these accessories now. Alright last thing, but I knew this before I bought it and it is something I can live with. Charging handle slide. In order to charge your rifle (or at least with mine) I have to move my buttstock back one notch from it being collapsed in order to cycle my rifle. Again I knew this and it is not a big deal to me.

    My conclusion, this is a GREAT product and one that I will be put to good use for years to come. Again I only had two gripes about it overall and they do not take away from the usability of the product.

  6. maxim.siryy

    Overall well engineered, lightweight and affordable product.
    Only one flaw noticed so far – cheek rest prevents charging handle from traveling all the way backwards on first 3 positions of collapsible buttstock, in other words if buttstock is completely collapsed, or on 1,2 or 3 position – operator cannot pull charging handle all the way.

  7. Tyler McDonald (verified owner)

    I have to say that Luth has nailed it with this stock. I have built a lot of rifles and searched for the perfect stock. I have found a few contenders but they are 3x the price and weight. The stock is great for precision work yet still light enough to run on my customers that compete in three gun competitions. My only complaint is that I just found this stock and could have been using it a lot longer. Great job Luth. Anyone considering this stock should also check out the chubby grip. It is a must have.

  8. RonGT

    Purchased the MBA-3 to replace factory stock on a Ruger Precision Rifle.
    Installation was easy and straightforward. Very pleased with this stock. Well made, easily adjustable (Ruger stock was a pain and the reason I replaced it) and very comfortable. Great product!!

  9. anthony paldino

    Great range of adjustments, solid, love the flat bottom with pic rail. Only problem – it was incredibly tight and difficult to get onto my Savage BA 10 Stealth……..its so tight – there will never be a rattle…..and not sure it will ever come off….

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Parts Schematic
The MBA-3, MBA-4 and MBA-5 Buttstocks require the use of a Carbine buffer tube. Use the diagram below to determine if you currently have an Carbine buffer tube. If you have an A2 Rifle buffer tube you may want to look at the MBA-1 or MBA-2 buttstock. If you are ordering an MBA buttstock kit, the proper buffer tube is included.

Further you will want to determine whether your buffer tube is a Mil-Spec or Commercial buffer tube.

Either one will work with your MBA Carbine buttstock, however Commercial buffer tubes are typically larger in diameter than Mil-Spec buffer tubes. The MBA Carbine Buttstocks will have more free-play on the Mil-Spec tubes than Commercial tubes. There is an anti-rattle set screw designed to tighten up the buttstock when used with a Mil-Spec buffer tube. The anti-rattle set screw should only be snugged up to remove the free-play, over tightening will damage the buttstock.

The differences between an A2 Rifle Buffer Tube and a Carbine Buffer Tube.

All MBA Buttstocks are Sling Swivel Ready.

This means that the buttstocks have molded pockets that accept Grovtec Sling Swivel Cups for use with Quick Detach swivels. The Sling Swivels and cups are NOT included with the buttstocks and must be ordered separately. This is to keep the cost of the MBA buttstocks down. Not every customer needs sling swivels and including them would raise the price of the buttstocks. The sling swivels are available separately. See the videos below for installation instructions using the install kit, or using a 1/4″ Allen wrench.

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