Complete LW-4 Lower – MILSPEC Stock

New Frontier Armory

(18 reviews) Write a Review
1.72 LBS
LW-4 Complete Lower
Black Polymer
Magazine Type:
Any standard AR-15 magazine

New Frontier Armory LW-4 Complete Polymer Lower Receiver

Manufacturer:New Frontier Armory

Model: LW-4

Type:Semi-Automatic AR-15 Lower Receiver


Magazine:Accepts any standard MIL-SPEC AR-15 magazine

Weight (unloaded): 24.8 oz

Other Specifications and Features of the New Frontier Armory LW-4 Complete Carbon Fiber Lower Receiver:

  • Pictogram style “SAFE” and “FIRE” markings
  • Caliber marking of “Multi” so it can be used with many different caliber uppers
  • MILSPECreceiver extension and stock body
  • Compatible with all standard AR-15 components and magazines
  • Manufactured to MILSPEC dimensions on state of the art injection molding machines and CNC equipment for consistent quality parts and exacting tolerances
  • Lightest most durable polymer lower on the market today
  • Low maintenance / easy cleaning / scratch resistant
  • “Zero Slop” fit eliminates the need for wedges — designed for an extremely tight fit at upper lug attachments in front and rear
  • Lifetime warranty against any manufacturer defects when used as directed
  • Save money by building your own AR-15 rifle from the ground up exactly the way you want it configured

*NOTE: Some .22LR, 9mm and other blow back style upper receivers use a groove in their BCG that is too narrow for the polymer hammer that comes standard on the New Frontier Armory LW-4 complete carbon fiber lower receiver. In these cases you will need to switch to a blow back style hammer available by clicking HERE. The blow back style hammer, once installed, will run all rim fire and pistol uppers, and still work fine with standard mil-spec rifle uppers.


OPTIONS: Also available in a stripped version.

AVAILABLE ACCESSORIES: Blow Back Hammer for use with .22 caliber uppers


Q: Can I build myupper while attached to the lower receiver?

A: NO!When assembling your upper receiver DO NOT torque the barrel nut or muzzle brake while the upper is attached to the LW-4 (or any other model) lower receiver. Assembling the upper improperly could cause damage to the lower receiver and will NOT be covered under the factory warranty.When assembling an upper you should use a reaction rod or a vise block specific for assembling upper receivers.

Q: Why is the safety selector able to turn to safe regardless of hammer position

A: This is an added safety feature that allows the firearm to be put on "Safe" whether the hammer is cocked or forward. We believe this is a much safer solution to ensure the safety of our users and will not affect normal use in any other way.

The New Frontier Armory LW-4 Complete Carbon Fiber AR-15 lower receiver is proudlyMADE IN THE USAby hard working American men and women and is covered under a lifetime warranty against manufacturer defects when used as directed.


This is a serialized item considered to be a firearm by BATFE. This item must be shipped to a Federal Firearm License (FFL) holder. All BATFE, GCA & NFA rules apply! This item must be shipped to a Federal Firearm License (FFL) holder. You will be prompted during checkout to pick an FFL to ship to in your area using our FFL Locate tool.YOU will be responsible for checking with your local FFL to ensure this weapon is legal in the state that you reside and that they will accept this weapon on your behalf and transfer it to you.New Frontier Armory, LLC will NOT be responsible for any shipping or admin charges incurred by packages not being accepted by the FFL you choose during checkout.

Weight: 1.72 LBS
Dimensions: 17.50 x 7.25 x 2.50 in

18 Reviews Hide Reviews Show Reviews

  • 5

    Posted by Steve Sortomme on 6th Dec 2023

    I have been looking at these complete lowers for a few years and have been reading the good reviews. I finally made the purchase. The shipping was fast and the product was completely assembled and ready to drop in my upper. My upper fit perfectly. The trigger pull is smooth and crisp. I am pleased with my purchase and will purchase again.

  • 5
    LW4 Polymer lowers

    Posted by RFO on 14th Sep 2023

    We love these!! Use them to put together various rimfire calibers for folks in this part of the country to protect their flicks from varmints. Trigger is much better than milspec, makes a great, easy to tote lightweight solution.

  • 5
    goes bang everytime!

    Posted by Larry Degala on 31st Aug 2023

    I had my doubts about plastic lowers for the AR15 rifle, but it works as flawlessly as an all-aluminum alloy MILSPEC lower. Everything is tight in fit and finish with the carbon fiber composite. The best magazines to do mag flips are the Lancer L5AWM. Everything is solid and it works 100%. I am very impressed with the plastic trigger and the plastic safety switch (the magazine release is metal to metal for durability and positive lock up). I purchased two lowers at the same time for a double-duty torture test for the next five years. We shall see!

  • 5
    New Frontier LW-4 polimer lower

    Posted by David Moore on 30th Aug 2023

    This is my second one, the first was bought some years back, (8 - 12 ?), I found that one to increase accuracy of loads with each upper I tried it with. This one is now under a short stroke piston upper, ( they can use a little weigh relief), I just shot it to check function , it ran smooth and turned in a .67" group with a Know Good Load for that upper, and @ 1/2 pound lighter... I like them and would put it on the line with one....

  • 4

    Posted by P S on 25th Aug 2023

    Okay, so I knew this was a base polymer lower. Lightweight and strong like the reviews and a friend of mine said. But I didn't know EVERYTHING was polymer, the safety switch, the hammer, other internals. I did NOT feel comfortable with a plastic hammer or retention pins; felt iffy about a plastic trigger. So I switched out everything for steel except for the safety selector. Other than that this thing does save some weight compared to an aluminum lower. Not that much though. Oh and the main reason it loses a star is that no magazines I have will drop freely after pressing the mag release. Even Pmags when fully loaded won't drop free. So I would never trust this thing to be a "SHTF" lower, it will simply be a lightweight hog hunting/range toy build when I get an upper for it.

  • 5
    Lw-4 Lower

    Posted by Emory cowan on 5th Jun 2023

    Love the price Have Numerous older model LW-4 , Great overall Value.

  • 5

    Posted by on 2nd Nov 2020

    I originally purchased this item in January of 2013. I mated it to a PSA complete M4-style carbine upper. All pins were replaced with aluminum, the fire selector is steel and the trigger/hammer/spring setup is the PSA enhanced trigger group. Everything else remained the same. I have had zero issues from this lower and my friends are jealous of the lightweight rifle I have as compared to theirs. My LW-15 lower has not shown any signs of wear. I regularly shoot both M855 as well as civilian .223 through my rifle. If I had to do it all over again, I would have bought 5 of these lowers at the same time. I was not paid to leave this review and am a real customer residing in Louisiana.

  • 5

    Posted by AR-Buster on 1st May 2020

    Between my son and me we have purchased about 18 of your polymer AR lowers. Started buying them for personal use right after the initial testing was finished. We have subjected them to all manner of abuse. Actually we gave a new meaning to abuse. You used to have an email from me with pictures in your store on the top of the back rear right display case. The email and pictures were of and about my polymer AR that I ran over with my Bush-hog, cut the upper apart with a saws all, replaced the takedown pins and the upper, shot a half inch group with it the next day. It is still in my rack. I run several 30s, 223s and a 358 MGP in the lowers. No need for wedges, special mags, pins or anything else special. They simply are great lowers, period.

  • 5

    Posted by on 20th Aug 2017

    Bought my first back in 2009, don't remember if it was called LW-15 or not? I have put a Stagg Arms 5.56 and Olympic Arms 7.62x39; both hit what I aim-and I only aim at what I want to destroy. Tremendously light, much so it makes the weapon very front heavy!!! There is no real weight at the rear end of the rifle, so don't consider using that end as a headsplitter. These should last a life which is variable. I was diagnosed sever anxiety and insomonia disorders. Not enough. 2 months ago with 3 bulging or burst vertebra,stenosis (sever scarring of the spine) and degenerative spinal disease. Not enough. Last week diagnosed with a massive malignant tumor in and around my thyroid glands,lymph nodes, etc. So lasting a life time for 57 year old is an interesting reflection and introspective pondering. I may do a last firearm build especially for my Dr. Nephew and his Sister Dr. Niece both can choose from may firearms collection. Many have asked me how many firearms I have; I'd sooner tell them my unemployed LWOP than answer their question(NOYDB). You NEVER HAVE ENOUGH of WORKING FIREARMS AND good quality will protected AMMO. I spent the first 20 years in marketing and pr asking people to donate blood to save others in hospital through the US. The 2nd almost 20 working for the Federal Gov't, as I was to old to join the military when 9Sept2000 brought the beginning of the war to our HOMELAND. Ten's of thousands have died and 40,000+ have been maimed protecting all of us. I finely got hired by the TSA (worst Federal Agency ever to my knowledge-all of them mostly are-biggest violator of EEOC Law is........... .....?????come on America you can guess it=USA Fed. Gov't). Then to the USAF as a gym trainer, sport field prep,etc. as a temporary full time emergency hire-the airmen wore being deployed.USAF Fed. park ranger/warden,US Army Fed guard/ police chemical weapens guard, US Army Civilian Police officer and armorer, V.A. Civilian Police Officer(shameful how they and the general public treat our Veteran), and then back to the USAF as a Physical fitness tester(I'd been hired with the assurance of being in the first bunch of the "guaranteed first hires" to start of the Civilian Police/Security Forces-let me sell you winning lottery ticket.I've Sworn my personal Oath to the Constitution of the US. For you that are truly privileged to be "allowed" to own a firearm and be raised up with one. Our ONE Nation Under God is tearing it's self apart AGAIN. After 9-11all the Liberal top to bottom begged, fake prayed for God to help us, all the while continuing to plot for all individual Citizens to be unable to legally possess, much less own a firearm equalized. An Armed Society, is a Respectful, well protected one. We've let the liberal insult our intelligence by telling us to let the Police protect us ONLY---when seconds count, the Police are 15 minutes away or more-they do Police reports about what happened,etc., poor victim.I'll always be and act like a Police Officer, I'm no better or worse than any else I'm paid to if necessary forfeit my life to protect-our current batch of P.O. for th last 10 years, are shooting civilians, unarmed criminals, armed and supplied with Military weapons and Vehicle as if they are at war with the civilian populace. I'll die with my firearms and leave them to family members that value Freedom enough to arm themselves are are willing to defend their family. May the Lord continue to Bless Our America-please.

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