Originally Posted By jwliv180:
I'm not sure I'd go for a single kit, but rather get separately
- a good set of punches (1)
- a good gunsmith screwdriver bit set
- small soft tipped hammer
- armorer's wrench (many options out there)
- torque wrench in the right range
- some of these from CountyComm.
- good safety glasses
- patience and a sense of humor!

I'm probably forgetting something, it's been a minute since I went through the tool-up process. So double check!

If you have a bench vice, an insert to hold the lower while you work on it can make some things easier. I have one that locks into the mag well, once the mag catch is installed.

(1) The custom punches for the bolt release install and removal, with flattened areas, can save you significant angst re scratches. If you get them a little bit of heat shrink tubing makes them even less likely to scratch.

If you're doing an upper as well as a lower I'd add a reaction rod or upper clamps (opinions vary as to which is better, I like the MI reaction rod but the ones Brownells sells work too).

Do have spare parts. Get an "oops kit" which has spare springs etc.

Do wear safety glasses. Springs tend to get lost "with authority" when they go.

Do take time to make sure you're installing the right spring in the right place and orientation. The takedown pin springs look a lot like the selector detent spring if you're not familiar with them, for instance. and they really shouldn't be interchanged.

Do stop if something doesn't feel right. While some parts are "friction fit" e.g. pinned, and some springs can be annoying, you shouldn't need a lot of force any place other than where you might expect it. The one exception I can think of to this rule might be a standard style trigger, which can be a bear to spring and get installed if you've never done it before.

Do spend some time to play with the trigger set on the bench, if you're not using a cartridge drop-in type. Make sure the springs sit on the hardware where they're supposed to. It can be wrong and "sorta" feel like it works. But it won't.

Do buy quality tools and parts.

Do consider getting a paper book with good pictures. Getting the pages a little mussed can be a better alternative than trying to work with with a tablet or laptop when your hands are grimy.

Don't rush it.

Originally Posted By ROMAD-556:
Spare take down detents and springs. They are cheap and you're gonna launch a couple at first. Everyone does, its a right of passage. Once they launch, you may recover them 1/100 times but typically they're gone for good.

Originally Posted By runguns:
this little guy right here is worth its weight in gold https://www.brownells.com/tools-cleaning/gun-tools/rifle-tools/bolt-catch-pin-punch/

and your thumbs will thank you for having this tool https://www.suppressortools.com/product/michiguns-ltd-4348/

Originally Posted By ROMAD-556:
Spare take down detents and springs. They are cheap and you're gonna launch a couple at first. Everyone does, its a right of passage. Once they launch, you may recover them 1/100 times but typically they're gone for good.

Originally Posted By BoiseG:


I did the same thing on my first build, launched the forward detent that is today, hiding out with the 10mm sockets somewhere in my garage.  

OP,

Once upon a time I was an A&P mechanic and also a Cummins diesel mechanic, so I'm all about tools and I went a little overboard buying them.   As mentioned above a pivot pin tool will make life easy.

Thoughts on some of the various tools I bought:  

I have a Midwest Industries (MI) Armorers Wrench and it is very nice. If you're buying an armorers wrench, this is the one I recommend.  What I like about it is it's not polished, the finish has a bit of texture or grit to it that I like because it gets a good bite on parts like the castle nut.  Highly recommend it.  For comparison, I originally bought a Forward Controls Design Joint Castle Nut Wrench and I didn't care for it. I thought the FCD tool would work better for torquing the castle nut because of its size, but it's opposite of the MI armorer's tool. The FCD wrench is polished and it definitely will slip off the nut if you're not careful. The MI armorers wrench works much better than the FCD wrench for torquing the castle nut.

I also bought the Midwest Industries Upper Receiver Rod, I found it on sale at Lanbo's for $87 (not a joke) so watch for a sale if you're interested.  It comes highly recommended by The School of the American Rifle YouTube channel, which by the way is my #1 recommendation, check out that channel.  However, unless I did something wrong, the rod doesn't work for installing the barrel into the upper receiver.  I found that the upper will insert too deeply onto the rod without the barrel installed, so to use the tool for barrel install, you must somehow prevent the upper from inserting too deeply onto the rod, otherwise the barrel will bottom out on the rod before fully seating into the upper.  I had a BCM upper which needs to be heated for the barrel install and I was concerned with the upper cooling before I could finagle the barrel into the hot upper, so for the barrel install, I ended up buying a  Wheeler Upper Vise Block Clamp.  The face of the Wheeler tool melted just a small bit when I was heating the upper, so one side is now dedicated for barrel installs.  

The final MI tool that I bought was the Lower Receiver Block, and I didn't find it as useful as I thought it would be, and to be honest I regret buying it. I used it to install the gas tube to the gas block, and install the trigger guard and that's it.  I think it would be more useful if they cut it so it would fit the lower while the grip is mounted.

If you're budget conscious, Real Avid makes well designed tools and they work great, but the material they're made of is full on cheap Made in China quality.  But they work, that's the important part.  lol  

Our very own Brownells also has an excellent video series for building an AR.  

Brownells - How to Build An AR-15: Your AR Build Made Easy

Originally Posted By CosaviK:
Use a Pliers wrench to press in pins.  Way easier than punches imho.