This is my personal list, but feel free to link to it and share the link. There are many suppliers, these are just the ones that I have worked with in the past, and I have my favorite vendors. You will probably notice that I don’t have Daniels Defense, Spikes, or Rock River, except where they are included at Brownells or Midway. I am not a fan, but please let me be clear in that I do not have anything against their quality or anything like that. I just like some components that are more cost effective.
Stripped Lower Receiver
I have gone back and forth multiple times on what I purchase. When I get 80% lowers, I get them from Tactical Machining, and when I get stripped lowers, I tend to go with Surplus Ammo most of the time, now.
Lower Parts Kit
I really like the ones from New Frontier Armory and Surplus Ammo. They are reasonable, and easy to polish up. I tend to stick to the basics and not spend much money on drop in triggers.
Butt Stock – They don’t all include the tube
I really don’t have a favorite, yet. Make sure the one you order comes with the buffer tube, or you will need to buy that separately.
Stripped Upper Receiver
Yep, I almost always purchase from Surplus Ammo.
Upper Receiver Parts – Dust Cover and Forward Assist
Barrel – Keep in mind a 14.5” needs to have a pinned flash hider/suppressor
I am loving the Faxon Firearms stuff. They make some really nice stainless steel fluted barrels. I also really like the barrels from CMMG.
Bolt Carrier Group
I know that Nickel Boron is not all that and a bag of chips anymore, but I love how easy they are to clean after shooting. The RF85 from Anderson are supposed to be even better. No matter what, you will always want to use a little oil.
Gas Block and Tube
A low profile gas block will almost always fit under a free float rail. I have never used an adjustable gas block before, not even on my 300 Black Out rifles. I haven’t had issues where the gas needs to be adjusted.
Flash Hider/Suppressor – Don’t forget the proper washer
Personally, I always buy the 51 Tooth ATN adapters so I can then use my ATN suppressor on any of my rifles. I really like them.
Lately, I am using the ALG Defense Ergo Modular Free Float rail. It is so much easier to align the gas tube hole, and includes the rail pieces if you want to add accessories. It feels really nice when shooting, too.
I strongly suggest a few tools for building an AR. They should include:
Roll pin holders/starters
Barrel nut wrench
Reaction Rod – One of these is vital in that they properly distribute the force when working on the upper
Upper Vise Block – This is an option instead of a reaction rod, but I don’t like the force that is put on the upper when using one.