Enjoy free shipping during the holidays! Shop now and get
Free Value Shipping
on most orders over $49 to the contiguous 48 states, DC and to all U.S. Military APO/FPO/DPO addresses.
Enjoy Our Extended FREE RETURNS
We want to ensure that making a return is as easy as possible! With our Hassle-Free, Extended
Holiday Returns, eligible orders placed from November 12, 2025 on will benefit from an extended
return deadline (January 13, 2026 or 30 days after receipt of your order - whichever is later).
We'll even cover the cost of return shipping. Learn more about our
Return Policy.
Please Enable Your Browser's Cookies Functionality
Cookies are not currently enabled in your browser, and due to this the functionality of our site will be severely restricted.
Web browser based cookies allow us to customize our site for you, save items in your cart,
and provide you with a great experience when shopping OpticsPlanet.
Your privacy is important to us, and any personal information you supply to us is kept strictly confidential.
If you cannot enable cookies in your browser, please contact us — we are always here to help!
JavaScript is blocked by AdBlocker or ScriptBlocker
We're sorry - it looks like some elements of OpticsPlanet are being disabled by your AdBlocker.
Unfortunately we are unable to offer our excellent shopping experience without JavaScript.
Please add "opticsplanet.com" and "https://opl.0ps.us/assets-ac483a73966/" to whitelist,
or disable AdBlocker for this site (please note that we do NOT feature any annoying ads on this website).
Thanks!
Your Browser is Outdated
Unfortunately, we are unable to provide an excellent shopping experience on your browser because it lacks modern functionality needed for us
to provide a fast, secure, and enjoyable experience. If you cannot upgrade your browser or use an alternative device to visit us,
please contact us at +1-800-504-5897 and we'll be happy to assist you over the phone!
Luth-AR 5.56 Complete Mark 12 Barrel Kit Up to 11% Off w/ Free S&H — 2 models
If you want to attach a push button sling swivel to the stock you will need a Grovtec threaded base cup sold at Optics Planet under that product code number GT-CUP.
Ordered and received on time. Everything was in perfect condition. put everything on my lower and went and shot. No problems what so ever. top-notch barrel and receiver. the bolt is military-grade. Will purchase another.
Unboxing review: Items were packaged properly and securely. There was no excessive packing grease, YAY! All parts were in good condition including the bolt and bolt carrier. The bore of the barrel was clean and the grooves looked flawless to the nake...
Read More...
Bought this for my first AR build and I gotta say was very pleased with Luth-AR 5.56 Complete MARK12 Barrel Kit. Shipping was fast and packaged nicely. Comes with the MBA3 stock, which btw looks and feels right because, of the adjustments one can mak...
Read More...
ATTENTION! We currently do not ship this product to AK, CA, HI, IL, NY, WA, P.O. Boxes, and U.S. Territories. Please see our policies for more information.
Product Info for Luth-AR 5.56 Complete Mark 12 Barrel Kit
The Luth-AR 5.56 Complete Mark 12 Barrel Kit features an 18 inch Mark 12 5.56mm barrel and a 15in KeyMod short mid-length rail, so you can build a customized upper to add onto your stripped lower receiver. These AR15 Upper Receivers by Luth-AR are built tough with 4140 Chrome Moly steel with a 1-9 twist rate to ensure the accuracy you need from your rifle. This Luth-AR 5.56 Complete Mark 12 Barrel Rifle Upper Receiver Kit is also designed with 6 lands and groves, so you can use a variety of accessories and optics with this barrel. Button broaching adds extra strength and prevents the parts from corroding over time. You can also mount a suppressor or any other device you desire with this kit. The Luth-AR 5.56 Complete Mark 12 Barrel Mid-Length RH Barrel Kit features an attachment rail on the handguard, so you can easily install an A2 flash suppressor or other device that requires a mountable rail.
Specifications for Luth-AR 5.56 Complete Mark 12 Barrel Kit:
Manufacturer:
Luth-AR
Caliber:
.223 Remington, 5.56x45mm NATO
Overall Length:
27 in
Barrel Length:
18 in
Stock/Brace Material:
4140 Chrome-Moly Steel
Barrel Profile:
Government
Gas System Length:
Rifle Length
Barrel Twist Rate:
1-9
Number of Sling Points:
2
Threads per Inch:
1/2x28
Handguard Type:
Free-Float
Muzzle Device:
A2 Flash Hider
Finish:
Manganese Phosphate
Color:
Black
Gun Model:
AR-15
Fabric/Material:
4140 Chrome Moly
Gas Block Journal Size-Diameter:
.750 in
Handguard Length:
15 in
Handguard Style:
Round Rail
Gun Rail:
KeyMod
Gun Type:
Rifle
Gun Make:
AR Platform
Additional Features:
Will need GT-CUP
Bolt Carrier Group Included:
MIL-SPEC
Charging Handle Included:
MIL-SPEC
Weight:
12 lb, 11 lb
Magazine Included:
No
Features of Luth-AR 5.56 Complete Mark 12 Barrel Kit
Upper Specs:
7075-T6 Forging
Hardcoat anodize Black
Bolt Specs:
Bolt: Carpenter 158 steel
Extractor: 4140 Alloy steel
Army Spec Heat Treatment
Manganese Phosphate
Bolt Carrier Specs:
Carrier: 8620 steel
Cam pin: 4340 Alloy steel
Carrier key: 4130 Alloy steel
Army Spec Heat Treatment
Manganese Phosphate
Barrel Specs:
18″ Mark 12 5.56 mm Barrel
5.56 mm
4140 Chrome Moly
Threaded Barrel - Thread Pitch 1/2 x 28
1-9 RH Barrel Twist
6 Lands and Grooves
M4 Feed Ramp
Button Broached
Package Contents:
Luth-AR 5.56 Complete Mark 12 Barrel Kit
Fully assembled Mark 12 5.56mm Upper with 15in Keymod Palm Handguard
Your Browser is Outdated
