Best and/or Cheapest lower parts or kit for an M4 / AR-15

For individual parts I get whatever is cheapest and I usually shop at Brownells. With the seemingly endless shortage of lower parts kits (LPKs) it is harder to bargain hunt. If you can get one for $60 or below, or even $70 then I would suggest just getting it. For a list and the classic pic of all the parts in an LPK click the link.

It can be frustrating to pay that much for a parts kit when you already have some of the parts. Or, you plan on upgrading the pistol grip, trigger guard, selector, trigger, hammer, takedown pins etc etc. But buying the other parts can end up being more expensive that just getting a kit and not using some parts. I have constructed a simple table to help you make the decision, comparing the Brownells price per part with Anderson MFG price per part. I picked those 2 to give what I feel is a good general idea of whether to just get a kit or not.

It is better to buy the parts separately or get a kit?

If you hate charts, the basics of it are this:

Brownells: Make your own kit out of parts individually - $100      From a Kit? $55

Aderson Mfg                                         individually - $125      From a Kit? $66


However, if you have your own trigger group and you want to part out the rest of the lower and say, include a Magpul trigger guard and grip, then you can get the rest of the non-trigger parts for about $60 with the Magpul stuff, versus about $50 without. Still a borderline decision at best, but if you want anything else upgraded from that point, it starts to be better value to just get the parts individually. Assuming of course, you don't want to use the spare parts from a kit to start a new build...

What really sucks about buying lower parts kits or individual lower parts is paying for shipping, or there being almost every part you want in stock. Generally, a parts kit or any parts will work out cheaper if you get it while ordering something else to save on shipping. Or you can do what I do and just buy more magazines everytime you order a small part, but that can get expensive fast. 

But thankfully, some vendors are offering semi-customized LPK's. Palmetto State Armory offers a large variety of LPK's with most of the typical upgrades you might want, like a Magpul pistol grip and trigger guard. They have 24 different kits right now. 

Are brand name parts worth the extra money?

In a word. No. They are not. I have picked up a lower parts kit as cheap as $35. In Vegas. They said it was from Colt but there was no way to tell and the trigger felt like it was dragging over gravel until I polished where it touches the hammer and disconnector. From Brownells a colt LPK will run over $130. Compared to less than $60. With no way of knowing if all parts came from the same shop or not.

I have never had a spring, detent, bolt catch or mag release, takedown pin or pistol grip screw fail me, nor heard of one that did. So unless there is an improved look or function to the part, just go with the cheapest available.

Price per part vs lower parts kit comparison table:

All prices accurate 4/18/2012 Brownells Anderson        
    DPMS Anderson MFG      
Lower Parts kit Front takedown pin/pivot pin $3.87 $4.93        
  Rear takedown pin $3.87 $4.93        
  Takedown/pivot pin detents (x2) $2.22 $2.64 Price is for 2    
  Takedown/pivot pin springs (x2) $1.62 $2.64 Price is for 2    
  Buffer retainer/detent $1.29 $1.53        
  Buffer retainer/detent spring $0.90 $1.14        
  Trigger guard $6.08 $2.75        
  Magpul MOE Trigger guard $6.90   (Screw comes with magpul)  
  Trigger guard roll pin  $1.00 $1.12        
  Magazine catch $3.90 $4.09        
  Magazine catch spring $0.50 $1.85        
  Magazine release button $1.94 $3.16        
  Bolt catch $5.00 $8.09        
  Bolt catch roll pin $1.06 $1.12        
  Bolt catch spring $0.98 $1.58        
  Bolt catch buffer/detent $0.92 $1.76        
  Pistol grip $4.00          
  Magpul MOE Pistol grip $16.90 $22.57        
  Pistol grip screw $1.21   Not needed with magpul moe  
  Pistol grip lock washer $0.75   Not needed with magpul moe  
  Safety selector $5.89 $9.48        
  Safety selector spring $0.89 $1.39        
  Safety selector detent $1.23 $1.76        
Total  Without fire control $49.12          
Total Magpul upgrade without firecontrol $59.88 $78.53 Anderson with regular trigger guard only
Fire control Trigger $10.06 $15.98        
  Disconnector $4.43 $6.05        
  Disconnector spring  $1.32 $2.29        
  Hammer $16.78 $15.84        
  Trigger/hammer pins (x2) $2.14 $2.12 Price is for 2    
  Trigger spring $1.66 $2.08        
  Hammer spring $1.43 $1.76        
Total fire control   $37.82 $46.12        
Total Price All parts $97.70 $124.65 Anderson with Magpul grip  





List of currrent LPK Prices:

  Comparison brownels DPMS LPK $55.00          
  Anderson MFG LPK $66.00          
  Rainier Arms DPMS LPK $60.00          
  Rainier Arms Rock River $79.95          
  Rainier Arms Stag/CMT $69.95          
  Midway Del-Ton LPK $59.99          
  Midway DPMS $58.99          
  Midway Daniel Defense $82.00          
  Cheaperthandirt DPMS $57.82          
  Cheaperthandirt doublestar $59.98          


The chart is intended to show that it is a no-brainer to get a kit, unless you can get a discounted rate for parts buy buying bulk, or you just want a few parts to finish out a single build.

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