LPK is an acronym that just rolls off the tongue. LPK stands for lower parts kit. When building a rifle, you can choose between stripped or complete lowers. If you take the stripped route, you’ll need an LPK to finish things up. All those slots, holes, and pen points will be filled by the various parts of an LPK. That seems simple, but nothing in the AR world is ever simple That’s why we’ve assembled a list of the best AR15 lower parts kit options for you.
Once you start shopping, you’ll find many options, and inside of those various options, you’ll find several different kits that vary a bit in the parts they contain. Of course, complete LPKs exist, but there are also LPKs that lack certain parts. Typically, they lack the parts that a shooter would be the pickiest about, including the trigger, pistol grip, and trigger guard.
Today we are going to make things a bit simpler. We’ve gathered some of the best LPKs on the market for your consideration. We also want to ensure you leave this article well-informed about finding the right LPK and what you’ll need to get your lower receiver setup for success.
What goes in a Lower Parts Kit?
Let’s break down all the parts required for a complete lower parts kit.
• Pistol grip
• Pistol grip Screw
• Pistol Grip Lock Washer
• Trigger Guard
• Trigger Spring
• Bolt Catch
• Magazine Catch
• Magazine Catch Spring
• Magazine Release Button
• Safety Selector
• Pivot Pin
• Takedown pin
• Trigger Pin
• Hammer Pin
• Buffer Retainer
• Buffer Retainer Spring
• Selector Detent
• Takedown Pivot Pin
• Pivot Pin Detent
• Takedown Pin Detent Spring
• Pivot Pin Detent Spring
• Selector Spring
• Bolt Catch Spring
• Disconnector Spring
• Ejection port, and
• Forward assist.
Yeah, there is a lot to it. But look how much there would be if you were doing the whole rifle!
Don’t be intimidated. It’s actually not all that hard if you’re careful. Point is, if you’re missing some parts, you need to recognize that.
Best Lower Parts Kits
Best AR15 Lower Parts Kits (LPK)
Here is a list of the top AR15 lower parts kit:
- Bravo Company Enhanced Lower Parts Kit
- Luth-AR AR15 Lower Parts Kit
- Aero Precision EPC MOE-K2 Lower Parts Kit
- SOLGW AR15 Blaster Guts w/ Liberty Fighting Trigger
- Midwest Trigger Kit
- Sionics Lower Parts Kit Enhanced
- Palmetto State Armory MOE Lower Build Kit
Top AR-15 Lower Parts Kit Specs
Below is a list of some LPK specs. Here you can compare and line up the specs from each product and help you make the best decision possible.
|AR15 Uppers||Trigger||Spring Steel||Pistol Grip||Ambidextrous Controls?|
|Bravo Company Enhanced Lower Parts Kit||BCM PNT Trigger Assembly||17-7PH Stainless Steel||BCM Pistol Grip, Mod 3||No|
|Luth-AR AR15 Lower Receiver Kit||LR-20 Trigger AR15||17-4 SST and various Mil-Spec steel wire||LR-25 A2, Black Plastic||No|
|Aero Precision EPC MOE-K2 LPK||Aero EPC||Mil-Spec||Magpul MOE-K2||No|
|SOLGW AR15 Blaster Guts w/ Liberty FIghting Trigger||Liberty Fighting Trigger||Mil-Spec||B5 Systems||No|
|Midwest Industries Trigger Kit||Drop-in cassette||Mil-Spec||Not included||Yes|
|Sionics Lower Parts Kit Enhanced||SIONICS Enhanced||Mil-Spec||Not included||Yes|
|PSA MOE Lower Build Kit||Mil-Spec MOE||Mil-Spec||Magpul MOE||No|
Best AR15 Lower Parts Reviews
You’ve seen our summary list of excellent LPKs for an AR-15. Now it’s time to examine each lower parts kit individually.
Bravo Company Enhanced Lower Parts Kit Specs
- Trigger BCM PNT Assembly
- Spring steel 17-7PH Stainless
- Pistol grip BCM Pistol Grip, Mod 3
- Ambi controls? No
Bravo Company Enhanced Lower Parts Kit Review
Whenever I need to find the right balance between affordability and high quality, I turn to BCM. BCM makes some rock-solid rifles and some of my favorite AR-15 furniture. They produce a little bit of everything, and the BCM Gunfighter AR-15 Enhanced Lower Parts Kit is a great addition to any rifle platform.
What’s so enhanced about this kit? Admittedly, it’s some crazy ambidextrous kit with a PDQ lever and short throw safety. It is designed to maximize fit with the widest variety of MIL-SPEC rifles. This means you get MIL-SPEC-style parts. The enhanced part comes from the enhanced PNT trigger assembly. The PNT trigger is built around the MIL-SPEC requirement. It’s an investment cast and not a simple MIM design.
BCM ensures it’s built within strict specs and that strict specification ensures you get a consistently smooth trigger pull. It’s not crazy light and falls into that duty and defensive category. Inside of that category, it excels and helps ensure accuracy is paramount. Another nice feature is the BCM Gunfighter Mod 3 grip. It’s one of my favorite grips and is designed around the modern carbine, not the full-length AR-15 rifle.
Beyond the trigger and grip, you get a BCM Triggerguard as well. That’s a nice touch. Every other small pen, detent, and spring are all built to the MIL-SPEC requirement to ensure they are consistent and in-spec. The magazine release, bolt lock, and safety aren’t fancy, but they work and will work for the life of your rifle.
Bravo Company’s Enhanced Lower Parts Kit
- Amazing Quality Control
- Excellent Duty/Defensive Trigger
- Awesome Grip Included
- Doesn’t offer any ambidextrous controls
BravoCo Enhanced LPK: Check Pricing
Luth-AR AR 15 Lower Parts Kit Specs
- Trigger LR-20 Trigger AR15
- Spring steel 17-4 SST and various Mil-Spec steel wire
- Pistol grip LR-25 A2, Black Plastic
- Ambi safety? No
Luth-AR AR 15 Lower Parts Kit Review
If you are doing a Blue Collar budget build, then Luth-AR has you covered. Luth-AR is fairly well known for its high-end precision-designed stocks for AR-15s. Pro shooters like Daniel Horner have long used Luth-AR stocks for their superior levels of customization and fit. They’ve dabbled elsewhere and, interestingly enough, make one of the best, bare-bones, MIL-SPEC, budget-friendly lower parts kits.
The Luth-AR kit isn’t fancy, but it only costs about sixty bucks, so… Anytime you buy anything labeled budget-friendly, it’s smart to exhibit a good degree of caution. With the Luth-AR LPK, you get a simple but well-made kit to outfit any standard lower receiver.
You won’t find any MIM parts here. In the past, some budget LPKs used MIM parts, including the hammer. This would result in breakages at high round counts; they don’t always hold up when stressed. The Luth-AR kit is all American-made and uses parts made of either investment cast or machine to MIL-SPEC drawings. The springs are a 17-4 SST and MIL-SPEC steel wire combination with certification.
While the Luth-AR kit is simple, it’s well-made and affordable. This kit does include your standard A2 pistol grip and metal trigger guard to top things off. If you aren’t looking to break the bank, but want to keep your rifle’s reliability and lifespan high, then Luth-AR has you covered.
- Super Affordable
- Well Made
- Complete Kit
- Nothing Fancy Here
Luth-AR LPK: Check Pricing
EPC MOE-K2 Lower Parts Kit Specs
- Barrel length 10.3″
- Handguard type Quad Rail
- Gas system Carbine length
- Ambi trigger? No
Aero Precision EPC MOE-K2 Lower Parts Kit Review
Aero Precision released a rather revolutionary PCC a couple of years ago. Like most Aero products, it was built for builders, and Aero sells the individual parts of pieces to the open market without complaint. The EPC lower parts kit is perfect for your next PCC build. It’s one of the few lower parts kits designed specifically for pistol-caliber carbines.
Aero Precision makes several EPC parts kits, with the main difference being the included grip. I prefer the MOE-K2, but any of the EPC parts kits are rock solid, and you get to pick and choose your grip.
With that in mind, what makes the EPC kits different and well-designed for PCCs comes down to the core construction details. These are tough kits designed for blowback-operated guns and rated for 9mm, 40 S&W, 10mm, and 45 ACP. Blowback-operated guns are violent. They treat internal gun parts downright brutally.
To counteract this, Aero Precision designed the trigger and hammer pins to take that abuse. These hardened pins will soak it up regardless of the power of your caliber, up to the mighty 10mm. On top of that, the hammer, trigger, and hammer springs are designed to ensure total reliability throughout a wide gamut of ammo types and primer considerations.
The EPC lower parts kit is a bit beyond complete by tossing in a pistol grip, but that’s hard to hate. It’s ready to outfit your PCC lower and keep running for thousands of rounds. Is this the best AR15 lower parts kit choice for you? Maybe not, but it very likely could be if you’re building an AR9!
Aero Precision’s EPC MOE-K2 LPK: Pros and Cons
- Short and compact
- RIS2 Rail maximizes space
- Grip and Rip charging handle is an excellent design
- Front heavy
Aero Precision EPC MOE-K2 LPK: Check Pricing
SOLGW AR-15 Blaster Guts With Liberty Fighting Trigger
- Trigger Liberty Fighting Trigger
- Spring steel Mil-Spec
- Pistol gripo B5 Systems
- Ambi trigger? No
SOLGW AR15 Blaster Guts w/ Liberty Fighting Trigger Review
If you want a lower parts kit that’s not crazy expensive but made with strict quality controls for an in-spec simple install. Sons of Liberty Gun Works AR-15 Blast Guts with the Liberty Fighting Trigger offers you that option. With a name like blaster guts, you know this isn’t your average company. SOLGW earned a quick reputation with the firearm community for making extremely nice rifles with the highest levels of quality control.
The SOLGW AR-15 Blaster Guts don’t come with anything too fancy beyond the trigger. Don’t expect any ambidextrous controls or oversized controls. What you get is a set of parts designed to be in-spec with strict adherence to the existing MIL-SPEC. This includes the steel mag buttons, the magazine catch, the bolt catch, and the safety selector. You won’t find anything built to ‘commercial’ grade her.
The Liberty Fighting Trigger is built for duty, and defensive use, so don’t expect a two-pound trigger that will brake when the wind blouse too hard. It’s a MIL-SPEC design, but the main difference comes from the quality of its construction. Most MIL-SPEC triggers break between six and nine pounds, but the Liberty Fighting Trigger will always break between 6 and 6.5 pounds and deliver a consistently smooth trigger pull.
Sons of Liberty Gun Works holds nothing back regarding quality control, and their blaster guts kit represents that. It might not be fancy, but it’s the type of LPK you put into a duty rifle and will last you years of hard use without complaint.
SOLGW AR15 Blaster Guts + Liberty Fighting Trigger: Pros and Cons
- Built to Strict Specs
- Awesome Duty Trigger
- Will Last Forever
- You’ll Find Nothing Fancy Here
Sons of Liberty Gun Works AR-15 Blaster Guts With Liberty Fighting Trigger Deals
Midwest Trigger Kit
- Trigger Drop-in cassette
- Spring steel Mil-Spec
- Pistol grip Not included
- Ambi safety? Yes, single stage
Midwest Trigger Kit Review
If you want to get a smooth trigger right outside the box, the Midwest Trigger kit might be the choice for you. While Midwest calls it the trigger kit, it’s not just a trigger kit. It’s a complete lower parts kit that includes all the necessities to complete your lower and to get you shooting. Not only do you get an awesome trigger, but the kit comes with a few nice touches that set it apart.
Let’s address the trigger since Midwest wants it to be the star of the show. This is a drop-in cassette trigger. That means the trigger, hammer, and springs are all contained to one drop in design. This makes installation simple but also offers you a superior trigger. The Midwest trigger is a 3.5-pound single-stage trigger system. That’s remarkably light and well-suited for ARs built for competition and precision. The light trigger makes it easy to work fast and helps keep your sight picture unmoved between shots.
Besides an awesome trigger, you also get an ambidextrous safety with a standard and short throw option, though this depends on your lower. You get a set of anti-walk trigger pins that ensure everything stays put. This is a concern with cassette triggers. They are super smooth, and the anti-walk pins ensure nothing comes loose.
Other than that, the LPK is pretty standard. A nice addition is the Magpul trigger guard, which is enlarged and well-suited for big hands and even gloves. Other than that, you get all the normal parts, pieces, pins, and springs. It’s complete and just waiting to find a home in your rifle.
Midwest’s Trigger Kit: Pros and Cons
- Awesome Trigger
- Complete LPK
- Ambi Safety
- Probably Costs More Than Your Lower
Midwest Trigger Kit Deals: Check the Price
Sionics Lower Parts Kit Enhanced
- Trigger SIONICS Enhanced
- Spring steel Mil-Spec
- Pistol grip Not inlcuded
- Ambi safety? Yes
Sionics Lower Parts Kit Enhanced Review
Sionics is a top-tier AR brand that has made its name by producing some of the best rifles on the planet. Rifles take parts, and if Sionics can build good rifles, they can make good parts, and that’s exactly what the Lower Parts Kit Enhanced offers you. Sionics holds nothing back with this kit, and it’s surprisingly affordable, although it doesn’t fall into the complete LPK category.
What we do get is most of the goodies. This includes all the necessary controls, the small parts, pins, and pieces, as well as the Sionics, enhanced trigger. There is no pistol grip or trigger guard with this kit. Those can often be a personal decision; to be fair, they’d be Non-Sionics parts anyway.
The name Enhanced might strike you as something beyond normal, and that’s very true. Off the bat, the enhanced trigger is the star of the show. It’s a MIL-SPEC type trigger designed to be refined and finished to provide a smooth, grit-free trigger pull with a trigger pull that averages out to 6.5 pounds. The enhanced trigger features a corrosion-resistant nickel PTFE treatment.
This treatment reduces friction and naturally improves the smooth nature of the trigger pull. The friction reduction also helps maintain its lubricity for long-term success. Even after high round counts, the trigger remains smooth. Beyond a good trigger, we get an ambidextrous safety with a long-left selector and a short right. Every little spring and pin is designed to be in spec and of the highest quality to guarantee years of rough use without complaint.
Sionics Lower Parts Kit, Enhanced: Pros and Cons
- Affordable Quality
- Extremely High Quality
- Great Duty/Defensive Trigger
- Standard Mag Release/Bolt Catch
Sionics Enhanced Lower Parts Kit Deals
Aero Precision 20-Inch Rifle Upper Specs
- Trigger Mil-Spec MOE
- Spring steel Mil-Spec
- Pistol grip Magpul MOE
- Ambi safety? No
PSA MOE Lower Build Kit Review
Last but not least is an affordable option that is literally everything you need to complete a lower. A lower parts kit traditionally doesn’t include the stock, buffer, buffer spring, or receiver extension, but this PSA MOE Lower Build kit most certainly does. Palmetto State Armory is the company responsible for putting a AR 15 in the hands of everyone who wants one, including creating a culture of building your own AR the way you want it.
The PSA MOE Lower Built Kit includes your basic lower parts kit and a Magpul MOE stock and Magpul MOE pistol grip, on top of everything necessary to install the receiving extension and buffer. If you already have your stripped lower, this is your one-stop purchase to complete it. Add your upper, then have a rifle. At the same time, it’s only about 100 bucks.
The lower parts kit is fairly plain. In fact, it’s about as simple and as standard as it gets. Nothing ambidextrous, nothing refined, nothing crazy innovative. Just a solid, well-made lower parts kit designed to outfit whatever lower you want to toss at it. If you are on the tightest of budgets, this is an American-made option that drops in without complaint. It won’t give you the best trigger pull, won’t satisfy left-handed ergonomics, and won’t blow you away. What it will do is work and won’t break the bank
PSA MOE Lower Build Kit: Pros and Cons
- Above and beyond complete
- Very affordable
- Easy to install
- Very plain
- Gritty trigger
Palmetto State Armory MOE Lower Build Kit: Check Price
Going Low with AR15 LPKs
I tried to include mostly complete lower parts kits on this list. Some of these kits might be missing a pistol grip or trigger guard, but the most important parts are included. When you start shopping, you might wonder how complete of a kit you should purchase.
That depends on how picky you are. You can save a few bucks by buying a kit that lacks a pistol grip. If you plan to purchase a very specific grip for your gun, then you go with the LPK you want without a grip. Swapping grips is one thing, but if you plan to remove your trigger and replace it, you can typically save anywhere from 20 to 40 bucks by purchasing an LPK without a trigger.
If you don’t care that much, then a complete LPK will save you the most money and simplify the entire process for yourself.
A lower parts kit is admittedly one of the easier choices you’ll have to make. They vary, but at the end of the day, they all basically do the same thing. I advise investing a bit in your LPK – make sure it’s the best AR15 lower parts kit for what you want to do. These are small parts that need to be properly made. Out-of-spec parts break easily and are more likely to be problematic during installation (if not during operation).
Just because you can buy a lower parts kit off Wish or Ali Baba doesn’t mean you should. Be selective, and make sure you get what you want. LPKs are everywhere, and you don’t have much of an excuse to settle for something poorly made.
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