AR-15 Lower Receivers

The AR15 lower assembly is the heart and soul of the AR-15.

There are a few tools that make it easier to assemble your AR15 lower kit, but none of them are necessary. The minimum requirements include a hammer and punch to drive in a couple of roll pins, a flat-blade screwdriver for A2 stock screw, and either a screwdriver or Allen key for the pistol grip screw.

• Roll Pin Punches - to drive roll pins (3/32", 1/8", 5/32"); these have a small raised projection in the face of the punch to automatically center the punch and prevent the roll pin from collapsing
  
• Roll Pin Holders - used to hold and start roll pins... very convenient
  
• Hammer - used to drive the roll pins
  
• #10 Flat-Blade Screwdriver - used for A2 stock screw and some pistol grips
  
• Block of wood - base to support receiver when driving roll pins
  
• Pivot Pin Installation Tool - handy tool if you build a few lowers
  
• Allen Key - used for some pistol grips
  
• Telescoping Stock Wrench - to tighten telescoping stock lock ring

Your lower receiver will consist of 30 parts not counting the stock assembly, the receiver, or the pistol grip. It is a good idea to lay all your parts out on a flat, light-colored surface so that you can verify all your parts are there, and find them easily when you need them.

Because of tight tolerances, some of these parts will be a tight fit. With the exception of the roll pins, no part should need to be hammered into place.

SPRINGS


• Bolt Catch Spring - easily confused with the disconnector spring; disconnector spring is tapered though.
  
• Buffer Retainer Spring - second largest spring in the kit.
  
• Disconnector Spring - similar to bolt-catch spring, but identifiable because one end is wide than the other.
  
• Hammer Spring - larger of the two similar springs.
  
• Magazine Catch Spring - this is the largest spring in the kit.
  
• Pivot Detent Spring - same as the takedown detent spring, so there are two in a kit.
  
• Selector Spring - similar to the takedown and pivot detent springs, but there will only be one of these.
  
• Takedown Detent Spring - same as the pivot detent spring, so there are two in a kit.
  
• Trigger Spring - the smaller of the two similar springs.
  

  PINS
  

• Bolt Catch Buffer
  
• Bolt Catch Roll Pin - smaller of the two roll pins.
  
• Hammer Pin - same as trigger pin; can be inserted from either side.
  
• Pivot Detent - same as takedown detent; both sides usually rounded.
  
• Pivot Pin - larger of the two large pins.
  
• Selector Detent - one end is flat, the other pointed.
  
• Takedown Detent - same as pivot detent; both sides usually rounded.
  
• Takedown Pin - smaller of the two large pins.
  
• Trigger Guard Roll Pin - larger of the two roll pins.
  
• Trigger Pin - same as hammer pin; can be inserted from either side.
  

   

• Bolt Catch
  
• Buffer Retainer
  
• Disconnector
  
• Hammer - will have a J-pin already installed.
  
• Magazine Catch
  
• Magazine Catch Button - some are plastic, some metal.
  
• Pistol Grip Lock Washer
  
• Pistol Grip Screw - some are Allen-head, some use a slotted pan-head screw
  
• Selector
  
• Trigger
  
• Trigger Guard - some are metal, some plastic. Will already have a detent installed on its front end.

 

Assembling An AR15 Stripped
Lower Part 1

Assembling An AR15 Stripped
Lower Part 2