MBA-4 Carbine Buttstock
The Luth-AR Modular Buttstock Assembly (MBA) for AR style carbines is designed to replace the standard buttstock on your AR. The MBA-4 is designed to work with a 6-position Mil-Spec or Commercial buffer tube. The MBA-4 is a direct replacement a standard adjustable carbine buttstock without additional Length-of-Pull or Cheek rise in a low-cost, lightweight, strong and high-quality design.
The MBA-4 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-4 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. 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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- MBA-4 Tech Tips / Schematic
- MBA Carbine Buttstock Requirements
- Sling Swivels
- Light weight stock to mount to a carbine rifle (6-positions mil-spec or commercial tube) – This is our carbine skullaton stock
- The MBA-4 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.
- Fits all .223 and .308 AR carbine style rifles
- Super Strong Glass Filled Nylon
- 21st century look
- Easy to replace and quick to install
- Uses 4 out of the 6 positions on a mil-spec or commercial tube
- Available in Black or Flat Dark Earth
- Lightweight buttstock for the carbine AR, weighing in at 9.5 ounces
- Easy to add our Cheek Piece: Cheek piece will add an additional 1″ height on cheek rest
- Easy to add our Butt Plate Assembly or 3-Axis Butt Plate Assembly: The assemblies will add an additional 1 1/16″ length of pull with extended length buttplate
- Adapts To Existing Commercial and Mil-Spec Buffer Tubes
- Certain after Market Commercial Buffer Tubes that exceed 1.1172″ diameter may not fit
- 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-4 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
- Picatinny Rail
- Revolutionary Anti-Rattle Set Screw
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
- 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.
The MBA-4 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 Spring
- Latch Plate
- Lock Ring
SKU: MBA4-B — Black
SKU: MBA4-FD — Flat Dark Earth
|Extended Length of Pull||
|Collapsed Length of Pull||
Black, Flat Dark Earth
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.