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Best AR-15 & AR-10 Lower Parts Kits (LPK)

Finishing up your AR-15 build and need a lower parts kit to finish out that stripped lower?

Aero LPK Parts
Aero LPK Parts

Nowadays…you can typically build an AR-15 that will perform better than a pre-built that costs 30-50% more.  

What’s more, you can get exactly the parts you want, and none of the ones you don’t.

A Few Of Our Personal AR-15 Uppers
A few of our favorite things…

Of course, to turn that lower into the beginnings of a rifle (or something you can slap together with a pre-existing upper assembly)…you’re going to need a lower parts kit.

Assorted AR-15 LPKs
Assorted AR-15 LPKs

It’s not sexy…but they contain all the itty bitty important parts that make your lower function like a champ.

We’ll cover what’s in a standard AR-15 LPK and our favorite picks.  Plus some AR-10 LPKs too since there’s some differences.

Table of Contents


What’s in a Lower Parts Kit?

Specifically, you’re going to need the following:

Trigger SpringBolt Catch2 - Takedown Detents & Springs
Trigger PinBolt Catch PlungerPivot Pin
TriggerBolt Catch SpringRear Takedown Pin
Hammer SpringBolt Catch Roll PinBuffer Retainer & Spring
Hammer PinSafety SelectorMagazine Catch Assembly
HammerSafety Selector DetentTriggerguard Assembly
Disconnector & SpringSafety Selector Detent SpringPistol Grip

Now, I can feel like 75% of you losing interest immediately when confronted with that parts list but in the words of the Hitchhiker’s Guide: 

I promise it’s easier than it looks.  

In fact, you can check out the whole process of assembling a lower and decide for yourself.  If you can hammer a nail and turn a wrench, you’ve got what it takes to build a lower of your very own (and building an upper isn’t that much more involved).

Trigger Hammer Pin with Punch
Trigger Hammer Pin with Punch

Wondering which one to pick?  Where to buy them? What to do if you already have a trigger?

Fear not, firearms aficionados.  

I’ve got you covered.

Best AR-15 Lower Parts Kits

These are the best lower parts kits out there and are the ones I keep coming back to for build after build. 

1. Palmetto State Armory

Palmetto State Armory might sell the most AR-15s in the country…so they are one of my go-to sources for anything AR-15.

PSA .224 Valkyrie At High Bar Homestead
PSA .224 Valkyrie At High Bar Homestead

I’ve built plenty of their lowers with their LPKs.  Check out all our reviews of their guns here.


It may not look like much…but the baggies are a lifesaver…they are broken down into areas of lower assembly.  So now you don’t have to guess which spring or detent is which.

And almost all their kits come with additional furniture…I particularly like their Magpul MOE sets since I would have added one anyways.

at Palmetto State Armory

Prices accurate at time of writing

Prices accurate at time of writing

Also note that most lower parts kits don’t come with buffer tube assemblies so PSA has those “complete” sets too.

at Palmetto State Armory

Prices accurate at time of writing

Prices accurate at time of writing

Check out the entire selection of build kits and LPKs.  Some have their upgraded EPT trigger which is Nickel Boron coated (silver colored) for better trigger feel.

What’s your take on the PSA LPK?

Readers' Ratings

4.97/5 (558)

Your Rating?

2. Brownells MOE

Brownells is the premier online retailer of gun parts and accessories, so it makes sense that they would have an LPK for sale. The Brownells MOE AR-15 Lower Parts Kit actually comes with the buffer assembly, and Magpul MOE stock and grip, as well as an Geissele trigger, which is why it is so expensive compared to others.

at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

This kit is great if you’re looking for getting some good parts out of the gate and don’t want to spend a lot of time picking out parts.  In other words, if you’re here more for the building than for the savings or the part picking, this is the way to go.

Not that these parts are bad, and it’s certainly very convenient to have everything you need to complete the lower in one contained package (and it’s over Brownell’s free shipping threshold too) but you can get better parts and save money if you shop individually.

3. Geissele Automatics Lower Parts Kit

Speaking of Geissele…they are known mostly for their triggers, muzzle devices, and handguards, but they make everything from complete rifles to parts kits as well.

And the Geissele parts kit is pretty great.

It’s precision machined with all the skill and accuracy you’d expect from Geissele, and the price isn’t half bad for a set this nice.  The only things that are missing are the pistol grip and trigger group.

Best Trigger-less LPK
at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

I’d personally recommend throwing your favorite grip on there, and coupling that with a matching Geissele SSA-E trigger, or some other equally awesome Geissele offering.

4. Aero Precision Lower Parts Kit

Looking for something no-frills when you already have everything else like the trigger and pistol grip?

Aero LPK
Aero LPK

The Aero LPK gets the job done at an affordable price of $25.

Aero LPK Parts
Aero LPK Parts

They’ve also done well in my Aero, Anderson, and PSA lower builds.

at Aero Precision

Prices accurate at time of writing

Prices accurate at time of writing

Looking for a more standard LPK with trigger and pistol grip?
at Aero Precision

Prices accurate at time of writing

Prices accurate at time of writing


Another huge manufacturer of AR-15 parts and LPKs…CMMG.

They also come with baggies…but theirs are color coded with a legend in the back of the box to tell you specifically what’s there.

CMMG LPK with Colored Baggies
CMMG LPK with Colored Baggies

Highly recommend the CMMG LPK for a first time builder who isn’t looking to upgrade their trigger and pistol grip just yet.

Now let’s move onto the AR-15’s big bro…the AR-10.

Best AR-10 Lower Parts Kits

Most AR-15 LPKs will work with the AR-10.  But since the AR-10 is shooting larger calibers, the receiver and magazines are much larger.

Because of that these are a few of the parts that are NOT interchangeable.

  • Bolt Catch
  • Bolt Catch Roll Pin
  • Pivot Pin
  • Takedown Pin
  • Buffer
  • Buffer Spring
  • Magazine Catch

There’s also two “patterns” of AR-10 lower receivers.  By far the most common is the DPMS variant.  Unless yours says it is the Armalite style…chances are it’s the DPMS.

1. DPMS AR-10 Lower Parts Kit

And because of that…we recommend going with the source of the receiver pattern.

at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

2. CMMG AR-10 Lower Parts Kit

Consistent with our AR-15 recommendations, we like CMMG’s AR-10 LPK.  My first AR-10 lower used one and it worked fine.

at Palmetto State Armory

Prices accurate at time of writing

Prices accurate at time of writing

3. PSA AR-10 Lower Parts Kit

PSA’s AR-10 is proprietary and works great (full review here), but their LPK works with DPMS patterned AR-10s from other manufacturers.

at Palmetto State Armory

Prices accurate at time of writing

Prices accurate at time of writing

They also have tons of other packages with different triggers and grips.

What If You Lose Parts?

Well, you could just order the part, probably from Brownells or the like, but shipping for one part is annoying.

If you’re going to make a hobby out of this, you are almost guaranteed to lose parts (springs and detents will go flying across the garage at some point), so it may make sense to invest in a spare parts kit like this one.  

Best Build Saver
at Cabelas

Prices accurate at time of writing

Prices accurate at time of writing

This kit gives you a spare of all the little springs and other fiddly parts you’ll need, as well as spares for when springs start to wear out and break down.

Upgrading From Standard Parts

Finally, I want to make a note about upgrading these parts kits.  Granted, a spring is a spring, but an upgraded trigger, buffer, grip, and stock can really make a huge difference in how your rifle performs.

The trigger is really going to be the single biggest performance factor for the speed and accuracy of your gun.

Tested AR-15 Triggers
Tested AR-15 Triggers

We’re coming out with a major update to our trigger recommendations, but for now these are the Best Drop-in AR-15 Triggers.

After that, start with your furniture and go with something like Bravo Company or Magpul, in whatever color and design you like, and at whatever price point matches your build goal.  See our favorites in Best AR-15 Furniture.

Parting Shots

That does it for lower parts kits.  You should now know what to look for, how to choose a lower parts kit, and what to buy, as well as how to move on from the standard parts kits.  

If you’re building a rifle, and you’ve got your lower, this should get you the rest of the way to completing it.

Don’t forget about taking a look at the Best AR-15 Upgrades [2018]!

Building a rifle?  Like these parts kits?  Hate these parts kits? Got questions?  Let me know in the comments below!

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22 Leave a Reply

  • tirod3

    I hasn't been my experience to build an AR for less than a separate upper and lower pinned together. That is because the parts, separately, are all retail, and the makers/assemblers of finished guns buy all their parts in bulk. They get a better discount when roll pins are shipped in quantities of 1,000 each, or hammers and triggers the same. They install, retail, and get their markup on the assembly. A kit maker buys in bulk, separates in bags, labels, then retails, with profit on the kit. There is no free lunch.

    Now add handling and shipping on all those parts you ordered separately, sitting on the kitchen table ready to assemble. I counted it up, over $125 in shipping alone on my first rifle, over $65 on the second. And I had thought I learned my lesson. I guess I did - saved about half in fees to get things to me.

    This time I'm handling it even more frugally, bought the lower at an FFL and got a decent one comparable to PSA without shipping without the FFL transfer fee, too. That saved me about $12 plus $25-40 - my previous FFL passed and a new one may not be as inexpensive as he was.

    Those are very much costs to include when you are building your own - expect to pay overall about 10% more doing it than buying one and you did very well. As I'm flush on A2 grips from other kits, I'm glad to see them finally being deleted. Ten years ago, you got one like it or not, now, at least there is a choice. And asking around with others who build, you may discover a more economical kit which isn't buying recommendations on the internet, with a stainless trigger and hammer, which works very well, for a bit less than those recommended.

    And yet, it's not the first time I've seen the high end kits ranked lower. Apparently someone paid more to get a better rating, just like Google takes money to put you first in the search listings. Yes, they do.

    July 24, 2021 3:12 pm
  • Ryan

    So how do you Palmetto State make it to number one and Geissele at # 4 Is this more of a intro review course or to prevent newer owners from getting sticker shock?

    July 17, 2021 3:03 pm
  • HueMungusWhuat

    So what are your thoughts with the Smith and Wesson lower parts kit? Ive read that they are the best around. Any experience with those?

    July 5, 2021 11:31 pm
  • Justin B.

    I love the site, the memes and gifs too! Been to a lot gun sites, this broke down everything about the AR into helpful guides. Keep the content coming!

    February 25, 2021 12:37 am
  • Mark Bowes

    Matt Collins ,

    I am viewing how-to's , self-help , diy video and reading latest news on what's current with collapsable stock AR-15"s .450 , .458 , .50 caliber rifles .
    I'm seeking 2.5-4.5lb trigger pull weights , 4140 / 4340 chromoly bull barrels 18-20"
    I liked the good , better & best article of lower receivers.
    I love partridge hunting and camping , makes me a self-preservation prepper.
    Any notes n tips on my D.I.Y. study ?
    Tanks ,

    January 11, 2021 2:17 pm
  • Ryan Moore

    Can anyone suggest "Bulk" AR 15/10 Spring kits? And if not that specifically, Bulk LPK's for either?

    October 11, 2020 5:24 am
  • jonathan mcgowen

    What about ambidextrous lower parts kits? Do they exist?

    July 23, 2020 4:08 pm
  • Tom Smith

    Has anyone ever had any issues with a cheap LPK? I've bought the cheapest I could find with no issues to date over the last 20 years.. Maybe I've been lucky... LOL... I have bought several PSA, DPMS, CMMG etc as well as drop-ins: Rise RA-140 and JMT Saber.. BUT.. Never had issues with a $30 LPK.. Especially after a little honing of the seer surfaces....Hmm...???

    May 24, 2020 11:18 pm
  • Andy M.

    Thanks for an article about a very overlooked area of builds. I have wondered quite often what expensive LPKs have going for them that budget LPKs don’t? And your input seems to confirm my personal opinion as a builder, as long as their in spec... nothing really different. However, I would like to mention my favorite LPK, and the only one that really stands about as being a little better/different... the STRIKE INDUSTRIES ENHANCED LPK. $40 w/o fcg & grip. Better mag release, bolt catch, & takedown/pivot pins than standard.

    March 20, 2019 8:26 pm
  • David

    What about the CMMG kits vs Geissele?

    Also from a comment you made to someone else, it’s sounds like quality is mostly irrelevant as long that the parts are the right size/spec??? Did I understad that correctly???

    Is the listed “oops” kit good enough quality you could take a Geissele kit, swap in all the “oops” kit parts and still feel 100% secure it will function as well??? Or was that a cheap oops option, but buying an extra lpk or 2 from Geissele to use as “oops” components be best for a patrol or PDW build that your and others lives will depend on???

    Like the other person kinda eluded to, I’d love to know more about which parts Geissele makes vs which ones they get from a common supplier that you would find in many companies kits. But I loved the article!!! Thanks!!!

    January 26, 2019 8:07 am
    • David, PPT Editor

      I've tried 6 or 7 different LPKs over the years, I've never had an issue with any of them in terms of long term durability. I have gotten ones that were flatly not sized right, but all I had to do was contact the retailer and was sent new ones.

      Even with "Opps Kits" I've never found a difference in the long term.

      There are finish differences, Geissele, Aero, and CMMG have always installed very smoothly and quickly for me. Anderson was a little rough but still worked.

      I don't know exactly part for part who makes what. Your best bet for that info would be to contact each of them and ask, but they might not release that information.

      January 26, 2019 10:30 am
  • operator1961

    Any opinion on the Wilson Combat LPK?

    January 8, 2019 11:31 am
    • David, PPT Editor

      I would highly recommend anything by Wilson Combat. Their Beretta parts, AR parts, 1911 parts, everything they make is outstanding. And their LPK is surprisingly well priced too.

      January 8, 2019 11:53 am
  • Michael

    Does anyone know how the Aero Precision LPK compares to these?

    January 3, 2019 1:52 pm
    • David, PPT Editor

      Highly recommend Aero LPKs. I've used them in several builds and have never had an issue.

      January 3, 2019 2:38 pm
  • David Nuckols

    excellent piece - thanks for the info

    October 4, 2018 8:23 pm
  • Jim

    I went the way of a PSA Magpul LPK, came with absolutely everything. Stock, Buffer Tube, Buffer and Buffer Spring and all of the little parts. The only thing that I would think about upgrading would be the trigger. All for a little over $100.

    September 17, 2018 2:04 am
    • Thomas J Smith

      You can get PSAs LPT NiB trigger and hammer for $29 a few times a year... :)

      May 24, 2020 11:21 pm
  • Bravo Tango

    When I comment on one of these, I generally try to further the conversation, not to be critical. That being said, I don't see anywhere in this article that teaches how to choose an LPK, other than by price or the ones you like.

    Is there some info you can share on determining quality by materials used or how the parts are manufactured, i.e. forged, milled, cold wound springs, etc.? If not, I understand. If nothing else, you could emphasize using customer reviews as a tool to determine absolute quality or "bang for your buck".

    Thank you for sharing what you have thus far. I appreciate all the help I can get.

    September 10, 2018 10:00 am
    • David L

      Sadly this is one of those areas where it is very hard to tell who or how the parts were actually made. Many of the large brands don't actually make the parts themselves while still others make the parts themselves and for other major brands.

      Generally speaking though, since none of these parts is pressure bearing or have much mechanical value to them, they are unlikely to wear out or break even after tens of thousands of rounds. The main issue is that they need to be in spec from the start, but even that is mostly for installation rather than durability.

      My main goals when picking an LPK is that it comes with what I want (I generally get ones that do NOT have an FCG since I use aftermarket triggers), it is a decent price (around $50 or less), and that I get it from a company or retailer that I know has good customer service.

      I've had to return 2 kits for not being in spec, one was from a very good name brand and the other from a random no name. The no name about 80% of the parts were out of spec and the good brand only 1 part was out so they just sent me an oops kit to replace it.

      September 10, 2018 1:13 pm
  • Tyler

    How do you feel about the Anderson lower kit? I just recently built a lower using the stainless steel trigger kit and I'm liking it so far.

    September 7, 2018 1:58 pm
    • Tom Smith

      I've built several rifles/pistols using Anderson LPKs without issue.. As withe any trigger, if it's a little gritty or too much take-up(slop, creep etc) it is easily fixed. I like their speed hammers... and still buy Anderson when the price is right..

      May 24, 2020 11:24 pm