Build Your Own Premium Lower Parts Kit

I have been getting a lot of emails regarding where to buy a truly top-shelf lower parts kit (LPK). My answer has been something like, it doesn’t matter because none of them are readily available right now. However, I have given it some more thought and I realized that the days of the complete lower parts kit may be numbered – or at least they should be.

Many people buy a lower parts kit and then promptly replace nearly half of it with aftermarket parts. Why not just start with the aftermarket parts you want and then fill in with high quality components where necessary?

UCWRG Rifle Grip

UCWRG Rifle Grip

Spec Your Own LPK!

If I wanted to build the best rifle I could right now, I wouldn’t buy a complete LPK. I would buy a few select components and then fill in the necessary small parts with quality components.

I would start with an ALG Defense QMS or ACT Trigger. These triggers start with the best components which is important because if something breaks in a lower, it is often part of the fire control group. This will take care of the following parts:

  • Disconnector Spring
  • Hammer Spring
  • Trigger Spring
  • Trigger Pin
  • Hammer Pin
  • Trigger
  • Hammer
  • Disconnector
The new Battle Arms Development BAD-ASS-ST is an excellent selector.

The new Battle Arms Development BAD-ASS-ST is an excellent selector.

Next, I would add a top notch selector from Battle Arms Development. Take your pick. The BAD-ASS, BAD-CASS, and Short Throw variants are all great. This would take care the following:

  • Selector
  • Selector Detent

Choose which ever grip you prefer. I prefer the UCWRG grip. The grip is often the first thing to go on a new rifle. You might as well start with one you like. This would take care of the following

  • Grip
  • Grip Screw
  • Grip Screw Lock Washer
Manticore Arms SAGE Trigger Guard

Manticore Arms SAGE Trigger Guard

You could also add an aftermarket trigger guard like those from Magpul or Manticore Arms. This would take care of:

  • Trigger Guard
  • Trigger Guard Pins

What’s Left?

That would leave only the following parts for you to purchase separately:

  • Bolt Catch Spring
  • Buffer Retainer Spring
  • Magazine Catch Spring
  • Pivot Detent Spring
  • Selector Spring
  • Takedown Detent Spring
  • Bolt Catch Buffer
  • Bolt Catch Roll Pin
  • Pivot Detent
  • Pivot Pin
  • Takedown Detent
  • Takedown Pin
  • Bolt Catch
  • Buffer Retainer
  • Magazine Catch
  • Magazine Catch Button

Most of these are available from Colt individually through Colt lower parts are widely regarded as the best made. If they are too rich for your blood or out of stock, substitute in another brand. I think you may have better luck finding individual parts than finding complete parts kits.

I wish I started my builds this way the first time around.

5 Responses to Build Your Own Premium Lower Parts Kit

  1. B P Moffit January 4, 2013 at 13:55 #

    This is exactly the information I was looking for

  2. KD January 4, 2013 at 15:03 #

    This is ridiculous! Buying the “What’s Left?” portion of the list individually is VERY expensive. Perhaps you could source a LPK without the grip or trigger and save a little.

    • Matt January 4, 2013 at 15:15 #

      Colt lower parts kits run $200+. They aren’t cheap to begin with.

  3. Rob January 4, 2013 at 19:47 #

    It’s also a great way to build them exactly the way YOU want as your budget allows!


  1. Cool Guy LPK from Weapon Outfitters | Jerking the Trigger - January 21, 2014

    […] the height of the panic buying, when lower parts kits (LPK) were hard to find, I wrote about assembling your own lower parts kit with premium parts. It made sense then because you could more easily find the individual premium parts than the full […]

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