What’s included in an AR-15 lower parts kit?

An AR-15 lower parts kit includes pins, springs, selector, magazine catch, bolt catch, trigger guard, and sometimes a fire control group (trigger assembly).

Should I get a kit with or without a fire control group?

If you plan to use an aftermarket trigger, choose an LPK without FCG. If you want a complete drop-in kit, go with one that includes the trigger group.

Will these kits work with all AR-15 lowers?

Yes. These parts kits are compatible with all standard mil-spec AR-15 lower receivers including .223, 5.56, and .300 Blackout.

Are enhanced kits better than mil-spec?

Enhanced LPKs often feature improved ergonomics, tighter tolerances, or upgraded finishes — ideal for higher-end or competition builds.

Are these kits made in the USA?

Yes. All lower parts kits listed are sourced from U.S. manufacturers with a reputation for quality and reliability.

AR-15 Lower Parts Kit – Mil-Spec & Enhanced LPKs

**Deltac 28pc AR-15 Lower Parts Kit** $32.95

**Aim Sports AR-15 Lower Parts Kit** $61.95

**Timber Creek Outdoors AR-15 Lower Parts Kit** $89.99

**ERGO AR-15 Upper & Lower Spring Replacement Kit** $14.00

**ERGO AR-15 Lower Spring Replacement Kit** $7.45

**Aero Ar15 Lower Parts Kit Moe Blk** $119.36

**Aero Ar15 Lower Parts Kit No Fcg** $52.99

**Aero Ar15 Lower Parts Kit Moe Fde** $119.36

**Armaspec Superlight Lower Parts Kit .223/5.56-Black** $86.16

**Armaspec Gun Builder’s LPK less FCG & Grip for .223/5.56** $77.43

**Armaspec Lower Parts Kit less Trigger Group & Grip for .223/5.56** $81.80

**Armaspec Superlight Lower Parts Kit for .223/5.56 – Blue** $76.49

**Armaspec Superlight Lower Parts Kit for .223/5.56 – FDE** $86.16

**Armaspec Superlight Lower Parts Kit for .223/5.56 – RED** $86.16

**BATTLEARMS 3-Piece AR15/M4/M16 Enhanced Lower Parts Kit Specifications Reviews BATTLEARM** $43.94

**Bcmgunfighter Ar-15 Enhanced Lower Parts Kit** $123.07

**Daniel Defense AR-15 Lower Receiver Parts Kit – Semi-Auto** $126.19

**CMC Triggers Ar-15 Lower Parts Kit Without Grip/fcg** $49.63

**Kak Ar-15 Lower Parts Kit No Grip/trigger Guard** $54.69

**Kak Ar-15 Lower Parts Kit Basic Ambidextrous Build Kit** $43.38

AR-15 Lower Parts Kit – Complete Kits for Every AR Build

Build It Right From the Ground Up

A reliable AR-15 Lower Parts Kit (LPK) is essential for any rifle build or upgrade. Whether you're assembling a stripped lower, replacing worn internals, or customizing your setup, a high-quality LPK ensures every component functions with precision.

At Mounts Plus, we offer a wide range of AR-15 lower parts kits to fit your exact build goals — from complete kits with fire control groups (FCG) to minimalist kits without triggers or grips. We stock mil-spec and enhanced options from trusted names like Aero Precision, CMC, ERGO, Armaspec, BCM, and Daniel Defense.

Why Buy an AR-15 Lower Parts Kit from Us?

✅ Drop-In Ready Kits – Includes everything you need for your AR lower
✅ FCG or Non-FCG Options – Customize with your own trigger upgrades
✅ Mil-Spec & Enhanced Parts – Choose your level of precision
✅ Premium Brands – No generic no-name kits
✅ Made in the USA – Built to last and perform under pressure

What’s Included in a Standard AR-15 Lower Parts Kit?

Most LPKs include:

Trigger & hammer assemblies (unless specified without FCG)
Selector, detent, & spring
Magazine catch & release
Bolt catch & spring
Take-down pins & springs
Buffer retainer pin & spring
Trigger guard
Grip (or compatible with aftermarket grips)

Each kit clearly lists included parts. Kits without FCG are ideal for builders adding drop-in triggers.

Top-Selling AR-15 Lower Parts Kits

🔧 Aero Precision LPK

Available with or without FCG and MOE grip
Perfect for modern tactical builds
Precision-machined and 100% American-made

🔧 ERGO Enhanced Kits

Includes upgraded grip and spring sets
Ideal for ergonomic custom builds

🔧 Armaspec LPKs

Designed for builders using custom triggers
Includes enhanced takedown pins and springs

🔧 CMC & Daniel Defense Kits

Trusted in duty rifles and premium builds
Includes top-grade mil-spec components

🔧 BCM Gunfighter LPK

Minimalist parts with a reputation for reliability
BCM quality and tight tolerances

Types of AR-15 Lower Parts Kits

Kit Type	Ideal For
Complete LPK w/ FCG	Full builds or repairs needing all internals
LPK Without FCG	Custom trigger installations
Spring/Detent Kits	Maintenance or spares
Enhanced Kits	Tighter fit, better ergonomics & finish

Compatibility & Fitment

🔧 Fits all mil-spec AR-15 lowers
🔧 Compatible with multi-cal builds: .223, 5.56, .300 BLK
🔧 Works with pistol builds, carbines, and SPRs
🔧 All pins and parts match standard tolerances unless specified

Frequently Asked Questions

What’s the difference between LPKs with and without FCG?
Kits without fire control groups are made for custom triggers. Builders using drop-in or enhanced triggers often prefer these.

Do I need a special LPK for .300 Blackout?
No. Most lower parts kits are universal across AR-15 calibers like .223/5.56/.300 BLK.

Are enhanced kits worth it?
Yes — they offer smoother controls, better fit, and upgraded ergonomics like ambi safeties or anti-walk pins.

Will these parts work in a pistol lower?
Yes. As long as the lower is mil-spec, these kits are 100% compatible.

Are all these kits made in the USA?
Yes — we only stock quality U.S.-made LPKs from trusted firearm component manufacturers.

Related Upgrades

Complete Your Build with Confidence

A quality AR-15 lower parts kit is the foundation of your lower receiver — don’t compromise. Whether you’re building a lightweight rifle, a duty-ready carbine, or a competition-ready rig, you need trusted parts that fit, function, and last.

Shop AR-15 Lower Parts Kits at Mounts Plus now — fast shipping, top brands, and performance you can count on.

AR-15 Lower Parts Kit – Mil-Spec & Enhanced LPKs | MSP