Building an ar upper

1quick

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I've always just bought complete uppers but I picked up two stripped lowers for Black Friday and want to just piece together two guns over the winter, any tips, I really don't know a ton about building the uppers, I'd like to go with 18-20 inch barrels since I already have 2 with 16" barrels, not sure on the benefits of the different gas system lengths, feel free to recommend parts barrel manufactures and such I will be doing one of them in 7.62x39, I prefer the look of the 15" hand guards, and like stocks that have a different look rather than a standard type stock
 
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1quick

1quick

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I plan to just mess around with them also no specific purpose to the builds the 223/556 one will probably be scoped since my other one is iron sights and 16" barrel
 

muskie

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Check out Ballistic Advantage for barrels. They are pretty reasonably priced and seem decent quality. I got a 16" .223 Wylde and it has been awesome.
 

Mr_Roboto

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Okay, so as one that's built a few uppers here's a few of my points:


-Clamped/screwed gas blocks have mixed opinions. My clamped gas block from YHM hasn't given me any issues though in my small sample with a minor amount of shooting. Once again unless you want a sight or something I'm a fan of commodity parts here.-For the 7.62X39 gun I'd probably buy the bolt and the barrel from the same place, just paranoid since it's not a true AR pattern. Not too much a fan of the idea they seem super hit and miss for feeding etc no matter if it's an AK mag style or not.
-For rails, I bought the Nordic Components first generation rail. It doesn't have any sort of way to keep it from rotating other than the lock nut. It was $55 and fairly light but other than that I'd look for something nicer obviously. BCM KMR comes to mind if you want premium.
-I usually do "commodity" for the receiver its self, the FA/gas door and gas tube. I have heard that the billet uppers are stiffer which supposedly is an accuracy adder but at the same time no one even seems to have any ancedotal evidence that is quantifiable I have found.
-I will put as much of the budget as I can into the barrel. That's where accuracy really comes from.
-If you're doing an 18/20" barrel due to the longer dwell time I'd do rifle gas if you have all other choices being equal. You'll end up with a softer shooting gun and it will respect your brass more if you reload. I like 1/7 or 1/8 twist for my guns, 223 wylde/noveske chambering for accuracy. That said I wouldn't lose sleep over a shorter length gas system. Enough guns out there use em.
For a 7.62X39 gun I'd use what barrel length you want. Her's an article almost no difference. You may be able to milk some more out with reloads but case capacity could easily be an impediment. 7.62×39 mm Russian: Effect of barrel length on muzzle velocity | Rifleshooter.com
-Get an AR Wrench and you're probably covered on a torque wrench. You'll need em for the barrel nuts. Besides that get a vise block setup. You don't really need a ton of tools.
 

1MEANGT

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Okay, so as one that's built a few uppers here's a few of my points:


-Clamped/screwed gas blocks have mixed opinions. My clamped gas block from YHM hasn't given me any issues though in my small sample with a minor amount of shooting. Once again unless you want a sight or something I'm a fan of commodity parts here.-For the 7.62X39 gun I'd probably buy the bolt and the barrel from the same place, just paranoid since it's not a true AR pattern. Not too much a fan of the idea they seem super hit and miss for feeding etc no matter if it's an AK mag style or not.
-For rails, I bought the Nordic Components first generation rail. It doesn't have any sort of way to keep it from rotating other than the lock nut. It was $55 and fairly light but other than that I'd look for something nicer obviously. BCM KMR comes to mind if you want premium.
-I usually do "commodity" for the receiver its self, the FA/gas door and gas tube. I have heard that the billet uppers are stiffer which supposedly is an accuracy adder but at the same time no one even seems to have any ancedotal evidence that is quantifiable I have found.
-I will put as much of the budget as I can into the barrel. That's where accuracy really comes from.
-If you're doing an 18/20" barrel due to the longer dwell time I'd do rifle gas if you have all other choices being equal. You'll end up with a softer shooting gun and it will respect your brass more if you reload. I like 1/7 or 1/8 twist for my guns, 223 wylde/noveske chambering for accuracy. That said I wouldn't lose sleep over a shorter length gas system. Enough guns out there use em.
For a 7.62X39 gun I'd use what barrel length you want. Her's an article almost no difference. You may be able to milk some more out with reloads but case capacity could easily be an impediment. 7.62×39 mm Russian: Effect of barrel length on muzzle velocity | Rifleshooter.com
-Get an AR Wrench and you're probably covered on a torque wrench. You'll need em for the barrel nuts. Besides that get a vise block setup. You don't really need a ton of tools.

Good info here. To add, like said above, barrel is the most important. Honestly your best option in my opinion is shop PSA for a 20" CHF barreled upper with A2 front sight block. It will already come pinned and you can cut/grind down the sight gas block to fit under any free float rail. PSA Cold Hammer Forged and premium barrels are made by FN.

If you are dead set on building your own spend the extra time and money to have a low profile gas block pinned to the barrel. ADCO does them pretty reasonably and decent turn around time. They pinned my BCM Mod0 comp on my 14.7 CHF build.

For a longer barrel I would prefer a rifle length gas system. But mid length is fine as well.

I do not know much about the 7.62x39 conversions but I would more then likely just go with a 16" barrel. 18 or 20 is not going to gain you anything.
 

HiccaBurp

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Instead of 7.62x39 maybe look at 300 blackout? I believe there is more support for them on the AR platform
 

Mr_Roboto

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Instead of 7.62x39 maybe look at 300 blackout? I believe there is more support for them on the AR platform
The market for 7.62x39 is huge just an issue of stuff working well. I thing it will be a build where troubleshooting is mandatory.
 
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1quick

1quick

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The market for 7.62x39 is huge just an issue of stuff working well. I thing it will be a build where troubleshooting is mandatory.
Yeah one of my current ar's is 7.62x39 won't chamber around but I bought the upper years ago and it's too late to try and warranty it, I started messing with it the other day to try and figure it out pretty sure the company I purchased the upper from machined the bolt face too small, I was reading it should be .454 it's .434 the rim of the cartridge is .445 give or take .001 - .002 I've got a guy that's going to machine it a touch more for me
 

PJx5x

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I built my lower and upper, love the combo.

18" white oak armament barrel, rifle gas length. 1-7 twist. Stainless. Highly recommended

Nikon scope with the bdc thing. Was very simple to setup and I like it

 

Mr_Roboto

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Yeah one of my current ar's is 7.62x39 won't chamber around but I bought the upper years ago and it's too late to try and warranty it, I started messing with it the other day to try and figure it out pretty sure the company I purchased the upper from machined the bolt face too small, I was reading it should be .454 it's .434 the rim of the cartridge is .445 give or take .001 - .002 I've got a guy that's going to machine it a touch more for me

A new bolt by its self should be only 30-40 bucks. It may be cheaper unlesss you are talking a case of beer.

Hell you may call and ask anyways. The may tell you to pound sand but maybe not.
 
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1quick

1quick

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A new bolt by its self should be only 30-40 bucks. It may be cheaper unlesss you are talking a case of beer.

Hell you may call and ask anyways. The may tell you to pound sand but maybe not.
Yeah I might shoot them an email showing the bolt measurement, yeah the dude would most likely be doing the bolt work for very cheap, it's a hobby of his and all the people in my neighbor hood seem to trade work with each other rather than pay for stuff to be done
 
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1quick

1quick

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Watching some assembly videos, there's way less parts involved than I really knew about lol I guess I could have just taken one of mine all the way apart to find that out, but the build on the first one is a go I'll start a build thread when some of the parts arrive
 

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