The LUTH AR Lightweight 16" Rifle Kit with Adjustable Stock is a comprehensive AR-15 build package designed for shooters who want to assemble their own rifle without starting from scratch. This kit includes everything except the stripped lower receiver—a complete upper assembly, lower parts kit, and your choice of stock configuration, making it an efficient path to a finished 5.56 NATO rifle. Whether you're building your first AR or adding to your collection, this kit handles the complex machining and assembly work so you can focus on final assembly and customization.
The heart of the kit is a fully assembled upper receiver built around a 16-inch lightweight barrel in 5.56 mm. The barrel is button-broached 4140 chrome moly steel with a 1-in-9 right-hand twist, M4 feed ramps, and six lands and grooves—a proven profile for hunting, sport shooting, and general duty use. The threaded muzzle (1/2 x 28 pitch) accepts standard suppressors and flash hiders; the kit ships with an A2 flash hider installed. A .750-diameter gas block and carbine-length gas tube regulate the system, feeding a fully assembled .223-caliber bolt carrier group.
The handguard is a 15-slot KeyMod vented design that balances weight and modularity, letting you attach rail segments or accessories where you need them. You'll choose between the fixed MBA-1 buttstock or the adjustable MBA-3 carbine stock—both interface with the included lower parts kit to complete your receiver once you source a mil-spec stripped lower. The complete lower parts kit handles all the small components, springs, and pins required for function.
This is a genuine DIY platform: you supply the lower receiver, and the kit provides everything else. It's a smart choice for builders who want quality components and the satisfaction of assembly without the learning curve of individual part selection.
Key Features
- Fully assembled upper receiver with 16-inch lightweight barrel—ready to install on your lower
- 5.56 NATO/.223 Remington compatible with proven 1-in-9 twist rate
- Button-broached 4140 chrome moly barrel with threaded muzzle (1/2 x 28) for suppressors and accessories
- 15-slot KeyMod vented handguard for lightweight handling and accessory mounting
- Choice of fixed (MBA-1) or adjustable (MBA-3) buttstock to suit your shooting style
- Complete lower parts kit included; stripped lower receiver not included
- A2 flash hider and fully assembled bolt carrier group ready to function
Specifications
| Caliber | 5.56 NATO / .223 Remington |
| Barrel Length | 16 inches |
| Barrel Material | 4140 Chrome Moly |
| Barrel Twist | 1-in-9 Right Hand |
| Rifling | 6 Lands and Grooves, Button Broached |
| Muzzle Thread | 1/2 x 28 |
| Handguard | HG-V-15K Vented 15 KeyMod Palm Handguard |
| Gas System | Carbine Length with .750" Gas Block |
| Feed Ramps | M4 |
| Bolt Carrier Group | Fully Assembled .223 Caliber |
| Muzzle Device | A2 Flash Hider |
| Stock Options | MBA-1 Fixed Rifle Buttstock or MBA-3 Adjustable Carbine Buttstock |
| Included | Upper Receiver Assembly, Lower Parts Kit, Bolt Carrier Group, Stock of Choice, Flash Hider |
| Not Included | Stripped Lower Receiver (mil-spec recommended) |
Frequently Asked Questions
What do I need to complete this kit?
You'll need to source a mil-spec stripped lower receiver to finish the build. Everything else—upper assembly, lower parts, stock, and bolt carrier group—is included. Once you have a lower, final assembly is straightforward.
Can I choose which stock comes with this kit?
Yes. The kit is available with your choice of the MBA-1 Fixed Rifle Buttstock or the MBA-3 Adjustable Carbine Buttstock, so you can select the configuration that fits your shooting preference.
What caliber is this rifle kit?
The LUTH AR Lightweight 16" Kit is chambered in 5.56 NATO / .223 Remington and includes a matching bolt carrier group.
Is the barrel threaded, and what accessories can I attach?
Yes. The barrel features a 1/2 x 28 threaded muzzle, which is the standard pitch for most 5.56 / .223 suppressors and flash hiders. The kit ships with an A2 flash hider already installed.
