Assembling an upper receiver for an AR

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1-1 Banger

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Gonna take a whack at assembling my first AR from scratch, I've got the lower figured out, it's a big boys Lego set. However despite using an M4 daily and having intimate knowledge of how they work, I'm pretty intimidated about assembling my upper. Help :eek:
 
What's to be scared of? You've already assembly far more parts than the upper has...
 
Im in the same boat. I have a Delton stripped lower in my possession and a PSA enhanced lower parts kit on the way.

Im currently debating whether I want to build an upper or just buy a complete assembled upper. I can follow directions as well as anybody, especially youtube, writeups, etc, but my concern is surrounding headspacing. Is that something fairly easily done? Any other special tools required for the upper build?

All that to say.... yea, I'll be following this thread too.
 
Provided you have a good vice, the proper AR vice blocks, an AR armorer's wrench, a torque wrench, and patience, it's not all that hard at all. Plenty of Youtube videos out there will show you exactly what to do.
 
Don't overthink this. The only specialized tool you need to assemble an upper is a barrel-nut wrench.

Put the barrel into the upper receiver so that the indexing pin goes into the notch in the front of the receiver. Tighten the barrel nut hand tight. Assemble the upper and lower and sit on it, on a carpeted surface (this is called a "butt wrench"). Using the barrel-nut wrench and a small breaker bar, tighten the nut as much as you can and then back it off just enough so that a notch lines up with the gas-tube hole.

A torque wrench is not really necessary. Nor are specialized vise blocks unless you're disassembling an already-assembled barrel/upper receiver.

Headspace is not an issue if you're working with new, in-spec parts.
 
I would not follow AlexanderA's advice. Ar uppers and lowers are not designed to stand that kind of side load torque. Doesn't take much twist in a upper to make it useless and the ears on each will break easier than you think. You can get the proper tools for about the cost of an upper. Action block from Midway for 35.00, action wrench from same 20.00, torque wrench from Harbor Freight tool for 22.00, vise from just about anywhere 50.00. If you have a friend that has a vise and/or torque wrench, see if you can borrow. You could probably get by without the torque wrench, kind of hard to exceed 80 ft./lbs. with just the barrel wrench. Proper procedure to install barrel is to clean barrel ext., inside of receiver, receiver threads and barrel nut threads. Apply light coat of moly based grease to barrel ext, inside of receiver and threads and to barrel nut threads. Torque barrel nut to 30 ft./lbs 3 times. After the 3rd time if notch lines up with gas tube hole you are done. If not, continue torquing until notch aligns with hole, do not exceed 80 ft/lbs. If you can build a lower an upper is a cake walk but you have two routes you can take, do it correctly or guess.
 
I think the upper is easier than the lower. Only hard part is getting that damn gas tube pin in, unless you have the specialized tool for it, which I do not.
 
I've built 6 or 7 ARs back in the day. I've also done a lot of barrel and upper swaps. Buy a wrench and a block, set of punches and you're good to go. Pretty easy actually.

In fact I just got two PSA stripped A3 uppers sitting on my work bench right now I am using to upgrade some old A1 and A2 rifles.
 
The upper is easy. Go for it. The worst that can happen is you lose that tiny c clip. Ask me how I know. Good thing they are cheap.
 
"I think the upper is easier than the lower."

Nonsense. Not only is the upper the most-stressed part in the AR rifle/pistol during firing, but it requires the most specialized tools to assemble it correctly. Not using the proper blocks, for instance, will sooner or later result in non-repairable damage to an integral part.

otrman has the right protocol. Pay attention to his advice and buy the proper tools...you'll be glad you did.
 
I've built a lot of ARs.

My modus operandi these days is to build the lower, and buy the complete upper already together...
 
"I think the upper is easier than the lower."

Nonsense. Not only is the upper the most-stressed part in the AR rifle/pistol during firing, but it requires the most specialized tools to assemble it correctly. Not using the proper blocks, for instance, will sooner or later result in non-repairable damage to an integral part.
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It's certainly no harder.

There are definitely fewer fiddly and easily lost parts to deal with (like that dang forward take-down pin detent & spring! :) ). You just need to have the right tools and know what you are doing.
 
I would not follow AlexanderA's advice.
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Agreed.

No offense, but that's about the most backwoods way I've ever heard of assembling an upper, short of using a pipe wrench.

Use a vice with action blocks or soft pine blocks, make sure you get at least 50 ft lbs on the nut, then continue tightening until your notches line up for the gas tube.

*if using pine blocks (I do), it's pretty easy with a flat top upper. Just drill reliefs in the blocks for the pin blocks on the receiver (use a bit that is the same diameter of the block's width, so that they, too, are jammed into the wood, not floating in the holes), then clamp the thing sideways in a vise, cranking it down until the receiver has a good bite into the soft pine. Be sure to get the entire receiver clamped, though; if you only go between the pin blocks, you will almost certainly tweak it.
 
Buy the proper tools. You'll either use them again to build another or, worst case scenario, sell them when you're finished. Required tools cost less than $100 bucks if you buy decent ones. Closer to $60 if you watch for deals.

Use a torque wrench. There is a max. torque that is to applied, then broken loose. Re-torque to a minimum spec. and line up your gas tube relief cut in the barrel nut.

Brownells has an excellent tutorial online regarding building an AR from start to finish, as well as installing some of the more popular mods.
 
Use a torque wrench. There is a max. torque that is to applied, then broken loose.
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That's important when dealing with very tight fitting parts that need to seat, but really not necessary with the AR, as the barrel will not seat with a bias any different the second time you torque it than the first.
 
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No offense, but that's about the most backwoods way I've ever heard of assembling an upper, short of using a pipe wrench.
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Pipe wrench........I thought we could only use Vise grips.......
 
Not every upper receiver fixture works with every upper, in particular this applies to the "clam shell" type fixtures.

By now you're starting to realize that the single act of tightening the barrel nut has various practices and proponents. You've been exposed to a couple of the AR-15 philosophies already: The Pro-torque wrench vs the Anti-torque wrench cults; and the fixture vs fixture-free lifestyle. You have not yet heard from the graphite-is-Satan vs neutral-graphite lube PACs, so you will want to research that to add to the utter confusion of what exactly you should do when you take that fateful step of inserting the barrel extension into your upper receiver. Good luck and may God be with you.
 
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If you are mechanically inclined, and used to assembling things, there are lots of good videos showing the steps to do so. You do need to make sure the feed ramps of the upper and barrel extension match up well. It is best to check the headspace with gauges, or pay a gunsmith to check it, although many do not, and the vast majority of the time it is correct by all accounts. Still good insurance to do so.

It really isn't hard if you have mechanical ability as well as the ability to learn from videos. Most folks just buy an upper assembly.
 
If you feel the need to use a vise, rather than use the method I outlined above (which, btw, has worked well for me for quite a few builds), then clamp the barrel rather than the receiver. (Use hardwood blocks shaped to fit around the barrel.) The steel of the barrel can take a lot more clamping force than the aluminum receiver, and you don't need to bother blocking the receiver. The receiver won't turn because of the indexing pin.

Nobody has mentioned that the slip ring, spring, and snap ring have to be assembled on the barrel nut before it's put on the barrel/receiver. Also the gas block/front sight is put on after the barrel nut is slipped over the front of the barrel. (These things are sort of self-evident.)
 
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While this Khyber Pass Garage method of upper assembly may produce an adequate assembly, it is needlessly asking for trouble. Clamping a barrel instead of the receiver puts shear stress on the index pin and they have failed before. Claiming that using in spec parts negates the need for checking headspace is irresponsible for the reputation of this forum. How does one know a part is in spec, or account for tolerance stacking, without a gauge? Past successes in this method do not predict future ones.

OP, building an upper is easy and can produce a great product if you use the right tools. Brownells has some good AR builder videos too. However, with the cottage industry that has sprung around custom builds has prouced several rsources for buying the work already completed at competitive pricing.
 
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