AR10 vs AR15 762.39

fivepointstar · Apr 14, 2016

What are the advantages and disadvantage of the AR10 in 762 NATO VERSUS the AR15 in 762.39?? I'm not looking at the cost or parts but as far as shootability and accuracy.

Right now if I can't afford an AR10....is the AR in 762.39 a good alternative for distance shooting?

ziptiespec · Apr 14, 2016

Those two calibers are worlds apart ballistically. Define distance, what's the distance you're trying to shoot? Are we talking 300 yds, 1000 yds? The 7.62 NATO round is definitely better for reaching out there. Also, define "shootabilty". Like, recoil?

babalou · Apr 14, 2016

I am sure Chad will chime in. He would say to use a 300 blackout. Uses same parts as .223/5.56. Not different barrel, etc. there are good sites that compare the 300 to the 7.62x39 in the AR platform. I was also thinking the AK round but after reading what Chad PM'd me i picked up a complete CMMG upper in the 300. Have not shot it yet.

7.62x39 is cheaper to buy and shoot though

Sorry, different barrel but same BCG and CH. D'oh. Late and am really sick...

fivepointstar · Apr 14, 2016

ziptiespec said:
Those two calibers are worlds apart ballistically. Define distance, what's the distance you're trying to shoot? Are we talking 300 yds, 1000 yds? The 7.62 NATO round is definitely better for reaching out there. Also, define "shootabilty". Like, recoil?

I was afraid of that, I know they are like apples v oranges but it wuould be nice to shoot something comparable to the NATO round

babalou said:
I am sure Chad will chime in. He would say to use a 300 blackout. Uses same parts as .223/5.56. Not different barrel, etc. there are good sites that compare the 300 to the 7.62x39 in the AR platform. I was also thinking the AK round but after reading what Chad PM'd me i picked up a complete CMMG upper in the 300. Have not shot it yet.

7.62x39 is cheaper to buy and shoot though

I have a load of 762.39 and don't want to start into .308 or 300 blackout I'm just wondering how comparable it would be since I already have the ammo

E.Shell · Apr 14, 2016

I have an 16" Colt 7.62x39 and it shoots fine. The magazines can be problematic, but once you get them tweaked, they run pretty good.

Recoil is noticeably more than the 5.56, but not unpleasant.

Ballistics are closer to the .300 BO than they are to the .308, especially in the shorter barrels. If you envision ballistics similar to a .308, you will be disappointed.

Sticky · Apr 14, 2016

Agree with E Shell's post... it's no 308, but a tad more than the 300BO. I built two x39 AR's, both run fine, use std AK ammo that I already have, cheap and fun to shoot, but they can't hold a candle to my AR308's when it comes to reaching out there.

The pistol is a short barrel and really barks, the rifle is a 16" and is a little more pleasant to shoot, but I figured, if the S really hits the F, that having a platform to run AK ammo would be a good thing and since I'm not a huge fan of the AK platform, I went AR instead.

I also have a 300BO in a pistol configuration, but it's a little more involved to feed it as compared to some of the inexpensive AK ammo.

Semper Noctem · Apr 14, 2016

I would also recommend supersonic 300 blackout. All you need is a barrel swap and you have a kick ass 30 cal platform.

Throw a suppressor on it and smile.

erwos · Apr 14, 2016

If you are looking for a good alternative for distance shooting in a cheaper AR-15 form factor, 6.5 Grendel is worth looking at. The steel-cased ammo pricing is a real game-changer for that caliber.

That said, if your only criteria is "shoot far with .308", why not a cheaper bolt-action rifle? You can get a decent .308 bolt gun for $300-$400, or even splurge a bit and get something like the Remington 700 (very moddable) or Mossberg MVP (takes M1A and SR-25 mags) for ~$600-ish. A decent bolt gun can be a nice break from a semi-auto, too.

pwoolford · Apr 14, 2016

Biggest problem I've seen with 7.62x39 in an AR15 is mags. I cannot find decent 7.62x39 mags that run in my AR without lots of feeding issues.

vgplayer · Apr 14, 2016

Something to look into. AR with AK mags.

http://www.mdshooters.com/showthread.php?t=191915

alucard0822 · Apr 14, 2016

Difference is 7.62nato has almost double the power, can handle heavier bullets, and works at double the range, obviously you need an AR10 platform

7.62x39 is problematic, they can run, but the case taper goofs with feeding, needs a bolt, barrel, mags and some tweaking. I fired a CMMG mutant, uses a specialized lower that takes AK mags and was a fine rifle. I would go that way instead of building a standard AR15 receiver to run 7.62x39 if I were in the market. 300blackout IMO is an attempt to get 7.62x39 ballistics in an AR15 as simply and reliably as possible, with ammo that costs at least twice as much as 7.62x39.

ziptiespec · Apr 14, 2016

I found a thread on another site that has some interesting info on 7.62 NATO vs 5.56 vs 7.62x39:

http://www.sksboards.com/smf/index.php?topic=79382.0

Here are the two graphs where those three rounds are compared:

.223 Rem. 55-gr FMJ-BT 5.56 M193 duplication load by Winchester. BC .272
7.62x39mm 122-gr FMJ M43 duplication load by PMC. BC .292
.308 Win. 150-gr FMJ-BT 7.62x51 NATO M80 duplication load by Fed/AE. BC .456

Trajectory w/ 200yd zero

Energy Comparison

I'm curious about PSA's KS 47 (the link vgplayer provided). Seems like a good way to have the 7.62x39 round out of the AR platform.

Blazin · Apr 14, 2016

Everyone has their own set of standards, but personally I won't own an AR in 7.62x39 due to too many potential issues with bolts, and feeding due to the tapered case (mentioned above), and more mags. Instead I have a 300 Blk AR upper, which I reload ammo for. Took a nice 200 lb hog with it last year, but I digress...

IMHO erwos nailed it, sounds like you NEED a 6.5 Grendel. Great cartridge with impressive ballistics (very similar drop to 308 in my experience). Just make sure the bolt matches the barrel because there's Type I and type II chambers/bolts.

Good luck!

OrbitalEllipses · Apr 14, 2016

I'm so glad this conversation has moved to 6.5 Grendel. Though it's just an illusion of cheap ammo - are you really going to shoot steel cased crap that wears your barrel faster through whatever nice precision barrel ($400-600) you get?

smdub · Apr 14, 2016

Blazin said:
Everyone has their own set of standards, but personally I won't own an AR in 7.62x39 due to too many potential issues with bolts
...
sounds like you NEED a 6.5 Grendel.

FWIW, 6.5 Grendel uses the 7.62x39 bolt size. They are based off the exact same case. Any issue you have w/ a x39 bolt you can have w/ a Grendel bolt (and conversely, any solution for the Grendel can be used to improve the x39.)

OrbitalEllipses · Apr 14, 2016

smdub said:
FWIW, 6.5 Grendel uses the 7.62x39 bolt size. They are based off the exact same case. Any issue you have w/ a x39 bolt you can have w/ a Grendel bolt (and conversely, any solution for the Grendel can be used to improve the x39.)

Only Type I uses a 7.62x39 (0.125") bolt. Type II must use a dedicated 6.5 Grendel (0.136") bolt.

erwos · Apr 14, 2016

OrbitalEllipses said:
I'm so glad this conversation has moved to 6.5 Grendel. Though it's just an illusion of cheap ammo - are you really going to shoot steel cased crap that wears your barrel faster through whatever nice precision barrel ($400-600) you get?

Yes. Next question?

smdub · Apr 14, 2016

OrbitalEllipses said:
Only Type I uses a 7.62x39 (0.125") bolt. Type II must use a dedicated 6.5 Grendel (0.136") bolt.

I'm talking diameter. The diff between Type I/II is the depth (and the matching barrel reaming depth) to help the grendel w/ its longer extractor. One could ream a x39 barrel short and use a grendel type II bolt - no difference. 10thou difference bolt depth does not affect strength which is what limits all of them. There is a lot of bolt thrust w/ the larger face. We are getting a bit off topic

If the OP wants better accuracy from a AR15 he should just skip over Grendel and go to something like 6mmAR

(how's that for throwing gas on the fire! :lol2:

Though its actually probably cheaper to reload than the 6.5 in the long run.)

clandestine · Apr 14, 2016

Many have hit on the "common" issues with 7.62x39 in an AR. GOOD Mags are the biggest hiccup. The new PSA AR that takes AK Mags solves that problem from what I see.

Another problem is light strikes. Firing Pin Protrusion is critical for a reliable x39 AR.

Another problem wth AR's in 7.62x39 is the headspace spec. American 7.62x39 chamberings often use a commercial spec, where the european spec uses a spec called CIP Gauges. This somewhat piggybacks on firing pin and reliability issues.

I believe this is one of the issues some bolt action 7.62x39 rifles from CA and the SIG 556r Rifles had with them not igniting primers reliably.

Gskwared · Apr 14, 2016

pwoolford said:
Biggest problem I've seen with 7.62x39 in an AR15 is mags. I cannot find decent 7.62x39 mags that run in my AR without lots of feeding issues.

I currently have a X39 AR platform. I am running a WMD NiB bolt carrier with a cason engineering bolt and a cheap Radical Firearms complete upper with a Seekins FF hand guard and a 7.5" barrel. I use the new C-Products Defense 30rd magazines Gen III SS and they work flawlessly.

Links:
Mags
http://shop.lcjwholesalestore.com/3...-BUY-10-OPTION-762x39-CPD-STAINLESS-STEEL.htm

Cason Bolt:
http://casoneng.com

It is important to note that Cason is reworking their website and I had to call them to order the bolt.

My x39 AR has never had a hiccup or an issue and all I run through it is wolf or Tula ammo. It really is a fun gun to shoot and the recoil is suprisingly manageable. I will say that with a 7" barrel it is a flamethrower.

I don't know what CPD in the mag design but like I said, I have had a single issue with mine. I didnt need to dremel or file them in any way. Now my CZ scorpion trigger pack was another story.....

AR10 vs AR15 762.39

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