What do I need to do in order to build a 7.62x39 AR

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[ARCHIVED THREAD] - What do I need to do in order to build a 7.62x39 AR

Posted: 8/22/2017 10:56:30 AM EDT

Well I've been toying with the idea of taking my one AR that's been through every imaginable change possible and making it into a 7.62x39 AR.

It started life as a regular 16" heavy barrel DPMS that I had purchased while in Afghanistan. This was also around the same time as Sandy Hook, so I paid way way way more than I should have but being overseas and with limited internet access, I bought first one I could fine.

I've rebuilt this DPMS in several different configurations, always in 5.56. However, I got to looking last night and been thinking I want to build it into a 7.62x39

The rifle as it sits now is painted, so his will mainly a hunting rifle but will be also for fun. I know I need to get a new barrel, bolt carrier group, and magazines.

I've already got a ALG defense trigger installed, and the rail I'm running is an ALG defense rail as well.

Anything specific I need to make sure I do so I can build a reliable rifle?

Posted: 8/22/2017 11:06:31 AM EDT

[#1]

Radical Arms from Texas builds a decent one, AIM was selling them for 450 shipped once upon a time. I believe they were selling barrels and bolt assy as well. Its a fun caliber to shoot cheap and the bolt hold open after last round

https://www.aimsurplus.com/catalog.aspx?groupid=6504&name=7.62X39+AR+Accessories
eta link added

Posted: 8/22/2017 11:08:06 AM EDT

[#2]

You need to get parts.

Posted: 8/22/2017 11:16:43 AM EDT

[#3]

First you need a 7.62x39 upper. That's the easy part, and there are a few different choices out there.

Next you will need magazines. When Colt first started selling 7.62x39 ARs, they just provided them with a 20rd straight GI 5.56 mag, and told you not too load too many into it. If you load too many, the steeper taper of the M43 case causes the top rounds to start to nose under and it won't feed reliably. This solution works fine if you don't mind having 12-13rd magazine capacity.

You may also need to replace your hammer spring with something heavier to fire the notoriously-hard primers of milsurp 7.62x39 ammo. If you are buying American-made, commercial brass-cased 7.62x39, or reloading your own with standard primers, that step may not be necessary.

There are probably some US-made 7.62x39 magazines made these days that will work better than the old Colt solution.

If you're willing to use a different lower, then the "AR-47" type lowers have a different magazine well which accepts standard combloc 7.62x39 magazines, and that nicely addresses any magazine and feeding issues, at least.

Posted: 8/22/2017 12:26:57 PM EDT

[#4]

I forgot to mention in my first post that I'm looking to use the radical arms 16" midlength barrel and an AIM BCG.

For magazines I'm looking to use the C product magazine.

Posted: 8/22/2017 1:26:40 PM EDT

[#5]

built up 3, all i did was take .010 off the firing pin and they all work, CP mags are the way to go.

Posted: 8/22/2017 2:39:52 PM EDT

[#6]

I ordered a complete upper from PSA PA47 16" 7.62x39 upper w/BCG and Charging Handle, and CPD mags, and have 800 flawless round through it shooting cheap steel ammo. I beleive the barrel, BCG, and mags, are the only difference.

Posted: 8/22/2017 3:07:13 PM EDT

[#7]

Bolt, Barrel, Mags.

Posted: 8/22/2017 4:14:03 PM EDT

[#8]

Quote History

Quoted:
Bolt, Barrel, Mags.

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CPD GEN III MAGS
That and a RedXArms extended firing pin for $10 or $11 shipped.
Also, use standard strength hammer springs or a Geisselle trigger group.
All of the cassette type Trig groups that I tried(POF, BRO, Timney AR10...)will not fire hard primers of steel case ammo about 30% of the time.

Posted: 8/22/2017 8:16:03 PM EDT

[#9]

the AIM BCG's for 7.62x39 come with the right firing pin, no separate purchase necessary. speaking from experience.

with your ALG trigger, and CPD mags, barrel, you should be all set. if it's a carbine M4 config, with the std M4 buffer spring, you might need to step up to a H3 buffer. to be determined when you function test with live ammo for last-round bolt-hold-open.

Posted: 8/22/2017 8:57:05 PM EDT

[#10]

Looking around tonight, the build (once complete), will be assembled with the following parts:

Stuff I have
-DPMS lower/upper off original DPMS ride
-Milspec buffer tube
-BCM Mod 1 stock
-Spikes T2 buffer with silicon spring
-Tango Down grip
-ALG trigger
-ALG V2 rail
-Troy front /rear sight set

Stuff need to buy
-Faxon barrel This one
-AIM BCG This one
-C product magazines

Posted: 8/22/2017 9:01:57 PM EDT

[#11]

[Deleted]

Posted: 8/22/2017 11:17:35 PM EDT

[#12]

My Green Mountain 1:9.5 twist 16" barrel is a tack driver. I opted for a RCA BCG and do my own trigger work.

Posted: 8/23/2017 10:24:37 AM EDT

[#13]

Quote History

Quoted:
Looking around tonight, the build (once complete), will be assembled with the following parts:

<Snip>

Stuff need to buy
-C product magazines

View Quote

CPD or C Products Defense is what you want, not the standard C-products. northriverllc.com, aimsurplus.com, and a few other places carry them.

Are you reusing your gas block and gas tube? If not, you'll need those too. Oh, and ammo, possibly a new bore snake or chamber brush to clean with.

Posted: 8/23/2017 10:34:48 AM EDT

[#14]

Quote History

Quoted:

CPD or C Products Defense is what you want, not the standard C-products. northriverllc.com, aimsurplus.com, and a few other places carry them.

Are you reusing your gas block and gas tube? If not, you'll need those too. Oh, and ammo, possibly a new bore snake or chamber brush to clean with.

View Quote

On the barrel currently installed is a shaved down A2 front sight. Probably have less than 500 rounds through it as set up so I'll just pass it on to someone on the EE.

The radical arms barrel I'm looking at getting had the pinned gas block. Also it's a midlength so I'll just resuse the same Spike's Tactical melonite midlength gas tube that's currently installed.

I believe I've got a new brush somewhere, but that's not a huge concern. Easy to obtain.

More I read about what people have done to make them reliable the more I want to do it. Have built x2 300 AAC Blackout, enjoyed the round and only had one FTF issue with a certain type ammo. Just can't afford to buy as much bulk 300 as I can of 7.62x39.

Plus, don't reload currently and have a kid on the way so funds are tight

Posted: 8/23/2017 11:58:34 AM EDT

[#15]

Here's a video I made last month on this topic:

Tips on building a reliable 7.62x39 AR-15

https://www.youtube.com/watch?v=-HELihkBV0Y

Posted: 8/24/2017 7:57:31 AM EDT

[#16]

Quote History

Quoted:
Here's a video I made last month on this topic:

https://www.youtube.com/watch?v=-HELihkBV0Y

View Quote

Thanks, did I hear you correctly in video that you used the Radical midlength barrel?

Nice looking build

Posted: 8/24/2017 11:59:39 AM EDT

[#17]

Quote History

Quoted:
Thanks, did I hear you correctly in video that you used the Radical midlength barrel?

Nice looking build

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
Here's a video I made last month on this topic:

https://www.youtube.com/watch?v=-HELihkBV0Y

Thanks, did I hear you correctly in video that you used the Radical midlength barrel?

Nice looking build

He clearly used Faxon and stated that they had their MLGS worked out well with that cartridge.

I watched the whole thing and heard no mention of Radical.

If you do a search, Radical has had problems with barrels and barrel extensions untorquing under fire, especially in 7.62x39.

When Colt spent who knows how much money doing the RDT&E on 7.62x39 in the 1980s, they did many things that I never see being addressed in the current after-market, who seem to be totally ignorant of Colt's work on that project.

Posted: 8/24/2017 8:39:09 PM EDT

[#18]

Quote History

Quoted:
He clearly used Faxon and stated that they had their MLGS worked out well with that cartridge.

I watched the whole thing and heard no mention of Radical.

If you do a search, Radical has had problems with barrels and barrel extensions untorquing under fire, especially in 7.62x39.

When Colt spent who knows how much money doing the RDT&E on 7.62x39 in the 1980s, they did many things that I never see being addressed in the current after-market, who seem to be totally ignorant of Colt's work on that project.

View Quote

You are completely correct. I don't know why I had Radical stuck in my head. Heck, even the barrel I'm talking about using and put the link too is the Faxon barrel

Posted: 9/13/2017 1:39:18 AM EDT

[#19]

Where can one find a "Heavy / Extra Power" Hammer Spring?

I've looked under Palmetto State Armory & Primary Arms with no success.

Posted: 9/13/2017 4:16:21 AM EDT

[#20]

Quote History

Quoted:
Where can one find a "Heavy / Extra Power" Hammer Spring?

I've looked under Palmetto State Armory & Primary Arms with no success.

View Quote

Brownells be my first place to look, if not Midway.

Posted: 9/13/2017 4:28:43 AM EDT

[#21]

Quote History

Quoted:
Where can one find a "Heavy / Extra Power" Hammer Spring?

I've looked under Palmetto State Armory & Primary Arms with no success.

View Quote

Wolff springs

https://www.gunsprings.com/

Dealers everywhere have them also....

Id stay away if it isn't a Wolff...imho.

Posted: 9/15/2017 9:25:56 PM EDT

[#22]

Who makes a good reliable bcg for a 7.62x39 AR?

Posted: 9/15/2017 9:33:09 PM EDT

[#23]

Quote History

Quoted:
Who makes a good reliable bcg for a 7.62x39 AR?

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Toolcraft

Posted: 9/15/2017 10:09:41 PM EDT

[#24]

Quote History

Quoted:
Who makes a good reliable bcg for a 7.62x39 AR?

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Rubber city Armory

Posted: 9/15/2017 10:13:52 PM EDT

[#25]

Get this, it works.

https://www.midwayusa.com/product/104578/ar-stoner-ar-15-a3-upper-receiver-assembly-762x39mm-16-barrel

Posted: 9/16/2017 7:57:02 AM EDT

[#26]

Quote History

Quoted:
Who makes a good reliable bcg for a 7.62x39 AR?

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AIM Surplus

Posted: 9/18/2017 4:24:21 AM EDT

[#27]

http://palmettostatearmory.com/psa-pa47-16-carbine-length-7-62x39-nitride-upper-without-bcg-or-charging-handle-5164463801.html
Complete upper minus bcg for $150 shipped!

I have only used aim BCGs. Never needed to change the hammer spring or firing pin.

Posted: 9/18/2017 9:43:42 AM EDT

[#28]

Quote History

Quoted:

Thanks, did I hear you correctly in video that you used the Radical midlength barrel?

Nice looking build

View Quote

I'm using a Faxon mid-length in the video.

Radical Firearms uses a Carbine gas system with a .093" gas port (overgassed)

Posted: 9/22/2017 12:00:59 PM EDT

[#29]

Does anyone have one of these bolts?

AR15 7.62x39 Bolt Option#1

AR15 7.62x39 Bolt Option#2

Posted: 9/24/2017 6:16:49 AM EDT

[#30]

Quote History

Quoted:
Does anyone have one of these bolts?

AR15 7.62x39 Bolt Option#1

AR15 7.62x39 Bolt Option#2

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I have the LMT bolt in a pistol 7.62X39 with 1000 rounds on it.
So far all is good

Posted: 9/24/2017 8:01:50 AM EDT

[#31]

I just purchased a PSA Ar in 7.62-39 and a Bear Creek upper in same caliber. I have not shot them yet will I need enhanced firing pin? I see Red X Arms has some. Any other issues others have had with same guns/uppers?
Thank all!
Huck

Posted: 9/24/2017 8:08:23 AM EDT

[#32]

Quote History

Quoted:
I just purchased a PSA Ar in 7.62-39 and a Bear Creek upper in same caliber. I have not shot them yet will I need enhanced firing pin? I see Red X Arms has some. Any other issues others have had with same guns/uppers?
Thank all!
Huck

View Quote

With some ammo you might need a Wolff +15% hammer spring. I didnt need anything else, firing pin should be ok. I have the PSA.

SGAmmo had some 223 ammo that was manufactured with wrong primers they sold at a great discount you needed an extended firing pin for.

Posted: 9/24/2017 8:39:52 AM EDT

[#33]

I have not seen it mentioned that you will need a muzzle device. Not sure if the Faxon comes with one. I bought a complete upper from Sanders armory and it has ran flawlessly after I installed an enhanced firing pin from Red X. I also am running the C P Defense mags as opposed to the older C products mags. I recently got 2 ASC mags and they worked for the few rounds I put through them. They look identical except they are "parkerized" and the C P Defense mags are a slick black finish.