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AR-15
Build Kits

Everything to build a rifle except the serialized lower. NSPEC Innovations bundles matched AR-15 build kits, from full rifle kits and lower build kits to classic M16A4 and CAR-15 retro builds, so you order once instead of cross-checking a parts list. Add a stripped lower and finish it at home. And because a kit is not a firearm, it ships straight to your door with no FFL.

Know Your Kit

Three Kits, Three Jobs

The words "parts kit," "build kit" and "rifle kit" get used loosely, and buying the wrong one is the most common mistake in an AR-15 build. Here is the plain-English breakdown so you order exactly what your project needs.

Tier 1 · Smallest

Lower Parts Kit

The small internal parts for a stripped lower.
  • Trigger group & hammer
  • Safety selector
  • Magazine & bolt catch
  • Springs, pins & detents
Does not build a rifle
Tier 2 · Middle

Lower Build Kit

Everything to finish a lower, top to bottom.
  • Full lower parts kit
  • Buffer tube assembly
  • Buffer & spring
  • Stock & pistol grip
Completes your lower
Tier 3 · Complete

Rifle Kit

The full package minus the serialized lower.
  • Complete upper & barrel
  • Bolt carrier group & charging handle
  • Lower build parts
  • Stock, buffer & grip
Add a lower = full rifle
Shop By Build

Find Your Kit

Our kits are grouped by what you are trying to build. Pick the project, then grab the stripped lower and any finishing parts you want to customize.

01

Rifle Kits

The closest thing to a complete rifle in one box. Our 16-inch 5.56 M-LOK and 20-inch M16A4 rifle kits pair a complete upper with the lower build parts, so all you add is a stripped lower.

16" 5.56 Rifle Kit 20" M16A4 Kit
02

Lower Build Kits

Finish a stripped lower in one order. A lower build kit bundles the lower parts with a buffer assembly, stock and grip. The B5 Systems kit is a proven upgrade over bare mil-spec.

B5 Systems Build Kit Lower Parts Kits
03

Retro & Clone Kits

For the classics. Build a period-correct CAR-15 or a full-length M16A4, or grab an A2 stock kit to give a modern build that old-school profile.

CAR-15 Retro Kit A2 Stock Kit
04

Pistol & Color Kits

Compact and custom. Build a short AR-15 pistol, or make it yours with a colored build kit in Gold, Blue, Pink or Orange. Same reliable internals, your finish.

Pistol Build Kit All Color Kits
On The Spec Sheet

What's In A Rifle Kit

A rifle kit is built to give you everything but the one regulated part. Here is what typically ships in the box, and the parts you supply yourself.

In The Box

Included

  • Complete upper Barrel, gas system, handguard and muzzle device installed.
  • BCG Bolt carrier group, the action's engine.
  • Charging handle Chambers the first round and clears the action.
  • Lower parts kit Trigger group, selector, catches, springs and pins.
  • Buffer assembly Buffer tube, buffer and spring.
  • Stock or brace Fixed, adjustable or pistol brace per the kit.
You Supply

Not Included

  • Stripped lower The serialized firearm; buy through an FFL.
  • Magazine Add a magazine to feed the rifle.
  • Optic or sights Free-float rails leave room for both.
  • Basic tools Punch set, small hammer and a castle-nut wrench.
  • Upgrades Swap in your own trigger, grip or stock if desired.
  • Confirm caliber Match your lower and magazines to the kit.
Why Build From A Kit

Cost, Control, Know-How

Building from a kit has three clear payoffs over buying a complete rifle off the shelf.

Save

Skip The 11% Tax

  • No FET A complete rifle carries an 11 percent federal excise tax. A kit does not.
  • Buy once A matched kit costs less than sourcing every part separately.
  • Watch sales Kit pricing moves, so deals stack up fast.
Customize

Your Exact Spec

  • Modular One lower can run several uppers down the road.
  • Pick parts Choose barrel length, handguard, stock and trigger.
  • Learn it Assembling the rifle teaches you how to maintain it.

Frequently Asked Questions

  • What is an AR-15 build kit?

    An AR-15 build kit is a bundle of components that includes everything needed to assemble a rifle except the serialized lower receiver. Depending on the kit, that can mean a complete upper, bolt carrier group, charging handle, lower parts kit, buffer assembly and stock. You add your own stripped lower and complete the build at home.

  • What is the difference between a lower parts kit, a lower build kit and a rifle kit?

    A lower parts kit (LPK) contains only the small internal lower parts: trigger group, safety selector, magazine catch, springs and pins. A lower build kit adds the buffer tube assembly, stock and grip so you can finish a stripped lower completely. A rifle kit is the full package: a complete upper plus the lower build parts, so once you add a stripped lower you have a whole rifle. NSPEC carries all three types.

  • Do AR-15 build kits require an FFL?

    No. Build kits do not include the serialized lower receiver, which is the only part legally classified as a firearm, so the kit itself is a collection of unregulated parts and ships directly to your door. You buy the stripped lower separately through an FFL dealer. Note that barrels and high-capacity magazines have their own state shipping restrictions.

  • Do I still need to buy a lower receiver?

    Yes. Every build kit is designed to pair with a stripped lower receiver that you purchase separately through a licensed dealer. The lower is the serialized firearm and must go through an FFL transfer and background check. Budget roughly $100 to $200 plus any transfer fee for the lower.

  • Why build from a kit instead of buying a complete rifle?

    Two main reasons: cost and customization. A complete rifle carries an 11 percent federal excise tax that a parts kit avoids, and building lets you pick the exact barrel, handguard, stock and trigger you want. Assembling the rifle yourself also teaches you how it works, which makes maintenance and future upgrades easier.

  • What tools do I need to assemble an AR-15 build kit?

    Finishing a lower needs only basic hand tools: a punch set, a small hammer and a wrench for the castle nut. If your kit includes a complete upper, the hard barrel work is already done. If you are assembling an upper from parts, add an armorer's wrench, a torque wrench and an upper receiver vise block. Many first-time builders complete a lower with simple tools by following a guide.

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