New Frontier Armory

Complete LW-4 Lower – MILSPEC Stock

(17 Reviews)
Category: Complete Lower Receivers On Sale Lower Receivers
: LW-4 Complete Lower
: AR-15
BBL Length
: N/A
: N/A
Magnification Range
: N/A
Tube Size
: N/A
: N/A
: Black Ano

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
Size: N/A
Color: Black Ano

Reviews (17)

LW4 Polymer lowers

Written 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.

goes bang everytime!

Written 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!

New Frontier LW-4 polimer lower

Written 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....


Written 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.

Lw-4 Lower

Written by Emory cowan on 5th Jun 2023

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

Written 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.

Written 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.

Written 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.

Written by on 3rd Jan 2017

I have owned this lower for about 3 years now. this thing is awesome! I have put around 5000 rounds in to it and its still kicking. The blow back hammer is getting a detente in it. I would like to say good job NFA. Also the Customer support was awesome. I had a problem with my rifle when i 1st built it. It was the upper. I did kill my Magazine Catch after or around 4000 rounds Plus Drills. Most people well be lucky to hit 2000 rounds in the lifetime of there lower I replaced it with Metal Magazine Catch. it was like 10$.

Written by rmatthardin on 9th Apr 2016

I wanted to wait a bit before writing a review. You just can't give honest feedback with something so new. So, now that I've had this thing for a couple of years, I feel I can give an honest, as well as informed, opinion on the product. I FREAKING LOVE THIS THING! I set about building a bargain rifle. Which I did. Since then I've changed out a lot of the components and turned it into a pretty decent lightweight patrol carbine, But first... I actually put the rifle into a stressed position for six months to see how resilient this polymer lower really is. I changed the temperature up and down rapidly, and the humidity as well. Just being thorough. To this day it still functions flawlessly! I love the polymer lower kit in this thing too. The trigger is sharp and crisp, with a short reset and it doesn't creep at all. Don't let the, "plastic," parts fool you. It may look like an airsoft or toy, it is not! It is a precision crafted machine. Is it perfect? No, of course not. I do have a few minor issues with it. The hammer that's included will work with milspec BCGs, but some others have a tolerance issue. Not a big deal, just a minor issue. I swapped the grip for something a little more ergonomic and had to drop an extra roll pin in there to make the safety engage. The pivot and take-down pins are so stiff that I need a punch to remove them. Again, not a huge issue, but it is an issue. None of these things would prevent me from buying another, or recommending one to a friend on a budget. All in all, this is the BEST VALUE on a lower that I have found anywhere in the market. And as soon as NFA starts making this thing in FDE, I'm buying another!

Written by volpe.ryan on 5th Dec 2015

I was on the fence for a long time in regards to purchasing the NFA Polymer lower sue to other sites claiming lack of strength/durability. I went in and purchased a 5 pack and split with up a buddy. I can say in the last 2.5 years of heavy shooting on all 5 lowers, we have not had a single issue. That says a lot about the quality and consistency of manufacturing. We are running a range of uppers from 10" barrel pistol setup to 24" long range upper. We are not easy on these things by any means. The weight reduction is a huge plus. Running DPMS, Rock River Arms and other brand uppers, all perfect fitment. I will be purchasing more when back in stock! Thank you NFA for an awesome product. ~ Ryan

Written by David Famiglietti on 18th Jul 2015

Thanks for the feedback Kevin, we're glad you're happy with it!

Written by on 18th Jul 2015

I purchased 4 of the NFA LW-15 a year and half ago and they are AWESOME! Approx. 1500-1750 rounds shot and NOT A SINGLE PROBLEM! I have built the following: AR57 upper (5.7x28mm) top load eject's spent cartridge down magazine hole. Colt A3 Upper DPMS Oracle Upper All three are fantastic builds. Weight is excellent. Trigger is smooth. Actions and feed are excellent. Waiting on the fourth... thinking of going with a .308 build on it... but have not decided. Groups are spot on - 10 shots in half-dollar or less. Cost to build 1/2 or less than pre-built arms. Slyvnr

Written by dei214 on 2nd May 2015

I'll keep it short and sweet. You do not have to spend 1200 dollars to get a quality ar. I thought I had a problem with the NFA lower, As I was on the phone with NFA I found it was an adjustment. The lady on the line was very nice and helpful. I can not say enough good things about NFA's GREAT people. PSA upper NFA lower, 1200-1500 rounds with O problems. I will be using NFA for my next couple of builds. Thanks Dan K.

Written by on 31st Jan 2015

I have two of the NFA Polymer lowers and they both fit excellently with my five upper receivers. I was really impressed with how the trigger group preformed. The first receiver I mated with CMMG dedicated 22 LR upper and found it worthy of any caliber suited to the AR platform. So I purchased another for a 300 Blackout build. I decided to replace the polymer part with standard metal parts, just because I wanted to make the comparison. I emailed NFA and asked if I would encounter any fit problems. They quickly replied and said that if I sent them the receiver they would do the install for the price of the parts and explained that there would be some fitting and on what pats might need it. I decided to take on the challenge and do it myself. Here is what was found. The blot catch doesn’t need replaced because it is already metal but the detent on the end of the spring is polymer. I changed it to metal. The first receiver only needed some cleaning up of the magazine catch to get it to operate without sticking. Everything else went together like any Mil Spec receiver. The second one needed a little more fitting. The magazine catch was the same as the first receiver. I also need to spin a ¼” drill bit, with my fingers NOT a powered drill, to clean up the edges of the holes in the take down and pivot pin holes. I had to use a drill bit on the pivot pin spring and detent hole because it wasn’t deep enough to compress the spring and detent so I could install the pin. And again use your fingers to twist the drill bit it didn’t take but several thousands to get it to fit. I also had to take a few thousands off the rear edge of the magazine well to get the Pro- Mag polymer magazines to seat with the new catch. I used a DPMS & ALG triggers with JP 3.5 springs, giving them a 4.5 to 5 lbs. triggers. All in all I think the NFA LW-15 is a very well made and highly serviceable for the AR platform no mater what caliber you choose.

Written by on 2nd Dec 2014

I have had this lower(Cali model) for a little over a year now. Maybe 1000 - 1200 rounds down range and not one ftf or fte. The lower has yet to show any discernable wear. Fire control group really cleans up after about 200 rounds. I have it matched to a PSA 16" M4 Premium Upper which mates together as if made for one another. I have two other complete PSA AR m4's, uppers and lowers. I must admit that this NFA lower matches to the other two uppers just as tight as the upper its mated with, and functions as well as my PSA billet lowers. I will now be buying another NFA lower to mate to a 7.62 x 39 upper. Must admit I was skeptical about a poly lower, but I would defiantly recommend this as a great base for an AR build.

Written by earlcm on 8th Oct 2014

I mated a Precision Firearms Orion 6.8 SPC upper to the LW-15 Lower. It was an admittedly tight fit and I had to try a couple of different lowers at the dealer as the fit was so tight. No Accu Wedge needed here. Lightweight, tight fit. I use the carbine for whitetail deer hunting, home defense and target shooting. The trigger seems to have minimal creep (I have a Gisselle SSA in my Bushmaster). I may replace the pins someday as I just seem uncomfortable with the polymer pins, but I am in no hurry. I would defiantly recommend this to other shooters to try

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