MBA-4 Carbine Buttstock with .223/5.56 Mil-Spec Buffer Assembly


The MBA-4 adjustable Rifle Buttstock Assembly is a complete kit that includes everything you need to assemble a carbine buffer system on your .223/5.56 AR lower. The kit includes an MBA-4 Buttstock without Length-of-Pull adjustment or Cheek Rise in a lightweight, affordable carbine buttstock. Comes complete with Mil-Spec 6-position carbine Buffer Tube, .223/5.56 Buffer, Buffer Spring, Latch Plate and Lock Ring. The modular design of the MBA Buttstock allows you to configure your buttstock to your specific and personal needs. 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.


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Package includes:

  • (1) MBA-4 Modular Buttstock Assembly
  • (1) Carbine 6-Position Mil-Spec Buffer Tube
  • (1) .223/5.56 Carbine Buffer Spring
  • (1) .223/5.56 Carbine Buffer Body
  • (1) Latch Plate
  • (1) Lock Ring

The MBA-4 is our stripped down version of the MBA-3

  • Fits all .223/5.56 and .308/7.62 AR style rifles
  • Strong and lightweight, 10 ounces
  • Easy to Replace and quick to install
  • Super Strong Glass Filled Nylon
  • Available in either Black or Flat Dark Earth
  • Ergonomic
  • Easy to add cheek plate or buttplate (adjustable Luth-AR accessories)
    • If you are upgrading the MBA-4 stock with a cheek or butt plate assembly you will need to also purchase the MBA-4 upgrade package
  • 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.


  • Picatinny Rail
  • Revolutionary Anti-Rattle Set Screw*


  • Overall Length  7 1/2″
  • Weight: 9.5 ounces

Compatible Buffer Assemblies:

  • .223/5.56 Mil-Spec Carbine Buffer Assembly (Included)
    • Material: 6061-T6 Aluminum
    • Finish: Hardcoat Anodized Black
  • .223/5.56 Commercial Carbine Buffer Assembly (Included)
  • .308/7.62 Mil-Spec Carbine Buffer Assembly
  • .308/7.62 Commercial Carbine Buffer Assembly

Additional Information:

  • 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. 

It does not include the following items, they can be purchased on our website separately in the Accessories section:

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.



Additional information

Buttstock Type


Buffer Tube



.223, .223 Rem, .556 mm, 5.56

Buttstock Weight

9.6 oz



Cheek Rise


Overall Length

7 1/2"

Additional Length-of-Pull


Available Colors

Black, Flat Dark Earth


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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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