5 Best AR 15 Lower Parts Kits

Here are 5 best AR15 lower parts kits (LPK) to buy to finish your AR15 lower receiver builds. These parts don't need to be super fancy, and here are ones we recommend after years of AR15 building experience.

Most options here come without the buffer system or trigger.

psa ar15 retro lower
PSA ar15 lower parts kit

Palmetto State Armory is a company that focuses on civilian firearm ownership, and most AR15 components they made are in house without middle man, which means cheaper price for you.
Their AR15 lower parts kit include all the parts you need to finish the main lower receiver without the buffer system.

This LPK is for any AR15 builders who need everything to finish their lower receiver without the buffer system or the buttstock.

  • Includes Magpul MOE Pistol grip and trigger guard.
  • Includes Palmetto State Armory Defender Classic Lower Parts Kit.
  • The Defender Classic Lower Parts Kit includes a polished fire control group in nickel and a standard safety

If you want a complete lower receiver build kit with buffer and stock, please click here

Geissele Ultra Duty Lower Parts Kit - Includes Large Bolt Release

geissele ar15 lower parts kit

Geissele makes top tier aftermarket AR15 triggers, and they also have multiple product lines such as the URGI and Super Duty Rifles that mil-spec AR builders love.

This is their lower parts kit minus the trigger components and pistol grip. This kit is for anyone who may already have a drop in trigger or a grip they would like to use.

  • The same lower receiver parts used on SOPMOD URGI and all Super Duty Rifle line
  • All key parts are made of stainless steel, which is strong and won't rust easily.
  • The kit includes the Maritime Bolt Catch, which has rough surfaces and big buttons, and the Ambidextrous Super Configurable Safety, which lets you change the safety levers and feels good to use.
  • The Ultra Duty LPK comes with the Ultra Precision Trigger Guard, which is made of strong aluminum and looks nice.

Also check out the Super Duty build kit without the serialized lower receiver here

CMC Lower Parts Kit - Includes A Great Drop In Trigger

cmc lower parts kit with trigger

CMC makes great drop in AR15 triggers along side Geissele. This is their Single Stage, Small Pin, 3.5lb pull trigger lower parts kit without the grip. (Flat trigger option available here)

This kit is recommended for builders who want a basic lower parts kit with an outstanding trigger right out of the box.

This LPK includes all parts need to complete a M5 lower receiver build. Instead of a boring A2 style pistol grip, this one comes with a Magpul MOE SL grip with a PDW style grip angle.

AGL Defense Lower Parts Kit - Includes ACT Trigger

ALG ar15 lower parts kit

This LPK includes all the parts required to finish a lower receiver build, and the ACT (Advanced Combat Trigger) is smoother and sharper than a stock trigger. The sear geometry has not been changed from the standard profile so the high reliability that the stock trigger is known for is unchanged.

Trigger and hammer are made from true 8620 alloy steel military specification castings, correctly carburized, quenched and tempered for high surface hardness.

A full force hammer spring is used for positive ignition of all type of ammunition. Pull weight is above the U.S. Military minimum pull weight of 5.5lbs but does not reach near the upper limit of 9.5lbs. Generally, the pull weight is about 6.0lbs."

Main Lower Receiver Parts List

  • Bolt Catch Coiled Pin
  • Bolt Catch Plunger
  • Bolt Catch Spring
  • Buffer Retainer
  • Buffer Retainer Spring 
  • Fire Selector Hex Key (Radian Ambi Fire Selector)
  • Magazine Catch (Magpul BAD Lever)
  • Magazine Release Button
  • Magazine Release Spring
  • Maritime Bolt Catch Safety Detent
  • Safety Detent Spring Takedown Pin & Pivot Pin Detents
  • Takedown Pin & Pivot Pin Springs
  • Trigger guard
  • Trigger bow
  • Trigger hammer
  • Trigger Sear
  • Trigger Guard Pin
  • Takedown Pin 
  • Takedown Pivot Pin