Gas piston for 7.62x39 AR build?

Pistoler0 · November 20, 2020, 03:08 PM

Hello,

I am having my first ever AR rifle built by Atheris, in 7.62x39mm. Atheris rifles have an accuracy guarantee. I have never owned a semi-auto before and I know very little about them, all my past rifle experience is with bolt guns.

I chose the caliber because of cost (I like to shoot and I am on a limited budget), and also because living in Colorado I need .24 caliber or larger for big game hunting.

My question is: Do you know of any good gas piston kit for 7.62x39?
I am pretty sure that Atheris build is direct impingement, but I would like to have the option to change to a piston in the future when I have a bit more funds.

sevt_chevelle · November 20, 2020, 04:44 PM

Why?
You are building an AR in 7.62x39 because its cheap to shot, Russian ammo am guessing, but likely spending a good bit of money by having one built with a guarantee then on top of it throwing a piston setup at it.

I have a x39 AR, just took it out yesterday, letting a guy at work use it for deer hunting. Having never shoot the thing before, he proceeded to shoot a 5 shot group measuring just under an inch with cheap arse Russian wolf ammo. All with a barrel bought on clearance from Satern barrels for about 100 bucks.

I built it because I wanted an AR in 7.62x39 because the ammo is cheap and as a guy that reloads, its kinda nice not having to chase down and worry about my brass. The typical 1.0 -1.5 MOA it shoots is just icing on the cake.

50 shooter · November 20, 2020, 04:54 PM

Why not just buy another upper for the lower?

That's the thing about AR's and them being like lego's, just pull your x39 upper off and put another upper on.

Of course it has to fit the lower, if you have a .223/5.56 lower, the upper in a different caliber has to fit. Likewise if you have an AR-10 lower and want to swap uppers, it has to fit.

brasscollector · November 20, 2020, 05:11 PM

Going from DI to piston is likely to require a new upper receiver (plus a pile of other parts). So that's a complete tear down and rebuild and still only leaves you with one working upper.

Pistoler0 · November 20, 2020, 09:10 PM

You all have good points.

I guess I should wait to get the rifle first, shoot it for awhile, and not be thinking about the "next" thing to do.

jetinteriorguy · November 21, 2020, 06:46 AM

I’d stick with DI, nothing wrong with it.

T. O'Heir · November 21, 2020, 01:49 PM

"...need .24 caliber or larger..." The 7.62 x 39 is not suitable for large game. It's ok for white tail deer under 100 yards. A 6mm x 47mm Lapua with 100 grain bullets runs at or very close to 100 grain .243 Win. Mind you, elk will still be too big.
I don't think there is an AR suitable cartridge that's good enough for elk sized game. And an AR will attract all kinds of unwanted attention from LEO/CO's. Even though you are not doing anything remotely illegal.
Oh and just building an AR is going to strain a limited budget. Far moreso than buying one. Building a rifle is not the way to go on a limited budget.

jetinteriorguy · November 22, 2020, 10:04 AM

I’ve taken many large Northern White tail does out to 200 yds, running shots years ago when I still hunted. And this was with a Gen 1 Ruger Mini30 that’s supposed to be so inaccurate. I never had one run more than 50yds before expiring. Second, you can build/buy AR 10’s in more than a few pretty effective rounds even for Elk, I have one in 6.5 CM that’s easily an MOA shooter past 500 yds that I wouldn’t hesitate to use, another good choice would be in .308. I paid around $600.00 for my AR in 6.5CM as a complete rifle from PSA a couple years ago, not exactly a budget buster.

44caliberkid · November 22, 2020, 11:19 AM

As someone who likes to jump on anything new in AR, I resisted going gas operated, did a lot of research, and concluded I didn't need gas piston. Yet, I still have a Superlative Arms piston conversion sitting in the parts bin, waiting for ?. With the SA unit, you can use your stock upper receiver but you have to use their bolt carrier and gas block.
I built a 7.62x39 AR, direct impingement, using a KAK Industries barrel and bolt, on sale, and magazines made for 7.62x39. I probably have $300 in the whole upper. Shoots great, by the way.

Fishbed77 · November 23, 2020, 10:42 AM

Quote:

I’d stick with DI, nothing wrong with it.

This. ^

For your intended use, there are no benefits to going with a piston system, and likely a few negatives.

MGMorden · November 23, 2020, 10:32 PM

The accuracy guarantee won't likely be in place after you switch - piston driven guns tend to be a little less accurate than DI (more moving parts jostling the gun around).

Also, a piston driven system isn't really just swapping a few parts - you're changing out the entire gas system and will likely also need a new upper, handguard, etc.

IMHO, if you're doing a piston-driven gun start it out that way - don't start with DI and then try to back into a piston driven setup. Or better yet - get a different rifle design. AR-15's are DI guns and 99% of all the parts out there are geared that way. Once you step into piston driven systems there is no mil-spec to follow anymore - it's all proprietary.

Pistoler0 · November 29, 2020, 03:00 PM

Quote:

Originally Posted by MGMorden

AR-15's are DI guns and 99% of all the parts out there are geared that way. Once you step into piston driven systems there is no mil-spec to follow anymore - it's all proprietary.

This is good to know, I want to avoid proprietary setups as much as possible.

Pistoler0 · November 29, 2020, 03:11 PM

Quote:

Originally Posted by T. O'Heir

"...need .24 caliber or larger..." The 7.62 x 39 is not suitable for large game. It's ok for white tail deer under 100 yards.

Yeah I know, I have a bolt action Savage 12 VLP in .308 for big game which I LOVE to shoot as it is a tack driver.

My reason for going 7.62x39 with the AR build is affordability of ammo, since I like to shoot more than I like to hunt. But also, although I know (as you said) that the round is not suitable for big game, it would not be illegal if I did.

I don't like to own a rifle in a caliber not legal for hunting in my state. To me, it is like owning a vehicle that is not legal for public road use.

doofus47 · December 7, 2020, 10:46 PM

I built a 7.62x39 uppered AR for chasing deer in dark timber in Colorado, so I think I know where you're coming from. It's a good choice.
edit: sorry, to answer your actual question: you don't need a piston.
The surprise issue I ran into was that longer, heavier 150-grain soft, lead tip ammo had a feeding issue where cheap, practice FMJ didn't. FYI. I think that Hornady sells a cartridge topped with a smaller 125-ish? grain SST bullet with a nylon tip to promote expansion. They used to anyhow. That should knock down any deer out to 200 and group pretty close to your practice ammo.
Good luck out there. Send pics!

Pistoler0 · December 9, 2020, 02:26 PM

Quote:

Originally Posted by doofus47

I built a 7.62x39 uppered AR for chasing deer in dark timber in Colorado, so I think I know where you're coming from. It's a good choice.
edit: sorry, to answer your actual question: you don't need a piston.
The surprise issue I ran into was that longer, heavier 150-grain soft, lead tip ammo had a feeding issue where cheap, practice FMJ didn't. FYI. I think that Hornady sells a cartridge topped with a smaller 125-ish? grain SST bullet with a nylon tip to promote expansion. They used to anyhow. That should knock down any deer out to 200 and group pretty close to your practice ammo.
Good luck out there. Send pics!

Thank you doofus, that really helped.

Super Sneaky Steve · January 2, 2021, 08:18 PM

Everyone has an opinion I guess, but few actually answered the OP.

https://www.blackriflearms.com/

I prefer piston guns. They are great for many reasons. One of which is they are easy to clean if you shoot cast boolits.

I wanted an 80% gun in 762x39 and it's much easier for me to mill an AR lower than to do an AK build.

So far my BRA upper has been perfect with C Products mags.

If you want a piston get one. Don't buy a gun to please other people.

Ignition Override · January 5, 2021, 01:19 AM

Super Sneaky Steve:
"If you want a piston get one. Don't buy a gun to please other people". Perfect philosophy in a nutshell.

My choice in 7.62x39 guns (three imported AKMs plus an imported Czechpoint VZ-58) wouldn't please many people here, as if it should matter one bit.

Interesting how the cheaper Russian ammo - in the right gun with an AR's aperture or red/green dot sights etc - can be a different animal.

doofus47 · January 6, 2021, 09:35 PM

IO:

Quote:

My choice in 7.62x39 guns (three imported AKMs plus an imported Czechpoint VZ-58) wouldn't please many people here, as if it should matter one bit.

Everyone here loves VZ58s....

November 20, 2020, 03:08 PM	#1
Pistoler0 Senior Member Join Date: November 15, 2019 Location: Conifer, CO Posts: 632	Gas piston for 7.62x39 AR build? Hello, I am having my first ever AR rifle built by Atheris, in 7.62x39mm. Atheris rifles have an accuracy guarantee. I have never owned a semi-auto before and I know very little about them, all my past rifle experience is with bolt guns. I chose the caliber because of cost (I like to shoot and I am on a limited budget), and also because living in Colorado I need .24 caliber or larger for big game hunting. My question is: Do you know of any good gas piston kit for 7.62x39? I am pretty sure that Atheris build is direct impingement, but I would like to have the option to change to a piston in the future when I have a bit more funds.

November 20, 2020, 04:54 PM	#3
50 shooter Senior Member Join Date: August 6, 2002 Location: SoCal PRK Posts: 986	Why not just buy another upper for the lower? That's the thing about AR's and them being like lego's, just pull your x39 upper off and put another upper on. Of course it has to fit the lower, if you have a .223/5.56 lower, the upper in a different caliber has to fit. Likewise if you have an AR-10 lower and want to swap uppers, it has to fit. __________________ I see the world thru bloodshot eyes Streets filled with blood from distant lies The dogs of war never compromise, No time for rearranging.

November 20, 2020, 05:11 PM	#4
brasscollector Senior Member Join Date: July 26, 2015 Posts: 526	Going from DI to piston is likely to require a new upper receiver (plus a pile of other parts). So that's a complete tear down and rebuild and still only leaves you with one working upper. __________________ He may look dumb, but that's just a disguise. -Charlie Daniels

November 21, 2020, 01:49 PM	#7
T. O'Heir Senior Member Join Date: February 13, 2002 Location: Canada Posts: 12,453	"...need .24 caliber or larger..." The 7.62 x 39 is not suitable for large game. It's ok for white tail deer under 100 yards. A 6mm x 47mm Lapua with 100 grain bullets runs at or very close to 100 grain .243 Win. Mind you, elk will still be too big. I don't think there is an AR suitable cartridge that's good enough for elk sized game. And an AR will attract all kinds of unwanted attention from LEO/CO's. Even though you are not doing anything remotely illegal. Oh and just building an AR is going to strain a limited budget. Far moreso than buying one. Building a rifle is not the way to go on a limited budget. __________________ Spelling and grammar count!

December 7, 2020, 10:46 PM	#14
doofus47 Senior Member Join Date: June 9, 2010 Location: live in a in a house when i'm not in a tent Posts: 2,483	I built a 7.62x39 uppered AR for chasing deer in dark timber in Colorado, so I think I know where you're coming from. It's a good choice. edit: sorry, to answer your actual question: you don't need a piston. The surprise issue I ran into was that longer, heavier 150-grain soft, lead tip ammo had a feeding issue where cheap, practice FMJ didn't. FYI. I think that Hornady sells a cartridge topped with a smaller 125-ish? grain SST bullet with a nylon tip to promote expansion. They used to anyhow. That should knock down any deer out to 200 and group pretty close to your practice ammo. Good luck out there. Send pics! __________________ I'm right about the metric system 3/4 of the time.

November 20, 2020, 04:44 PM	#2
sevt_chevelle Senior Member Join Date: April 13, 2013 Posts: 324	Why? You are building an AR in 7.62x39 because its cheap to shot, Russian ammo am guessing, but likely spending a good bit of money by having one built with a guarantee then on top of it throwing a piston setup at it. I have a x39 AR, just took it out yesterday, letting a guy at work use it for deer hunting. Having never shoot the thing before, he proceeded to shoot a 5 shot group measuring just under an inch with cheap arse Russian wolf ammo. All with a barrel bought on clearance from Satern barrels for about 100 bucks. I built it because I wanted an AR in 7.62x39 because the ammo is cheap and as a guy that reloads, its kinda nice not having to chase down and worry about my brass. The typical 1.0 -1.5 MOA it shoots is just icing on the cake.

November 20, 2020, 09:10 PM	#5
Pistoler0 Senior Member Join Date: November 15, 2019 Location: Conifer, CO Posts: 632	You all have good points. I guess I should wait to get the rifle first, shoot it for awhile, and not be thinking about the "next" thing to do.

November 21, 2020, 06:46 AM	#6
jetinteriorguy Senior Member Join Date: April 28, 2013 Posts: 3,173	I’d stick with DI, nothing wrong with it.

November 22, 2020, 10:04 AM	#8
jetinteriorguy Senior Member Join Date: April 28, 2013 Posts: 3,173	I’ve taken many large Northern White tail does out to 200 yds, running shots years ago when I still hunted. And this was with a Gen 1 Ruger Mini30 that’s supposed to be so inaccurate. I never had one run more than 50yds before expiring. Second, you can build/buy AR 10’s in more than a few pretty effective rounds even for Elk, I have one in 6.5 CM that’s easily an MOA shooter past 500 yds that I wouldn’t hesitate to use, another good choice would be in .308. I paid around $600.00 for my AR in 6.5CM as a complete rifle from PSA a couple years ago, not exactly a budget buster.

November 22, 2020, 11:19 AM	#9
44caliberkid Senior Member Join Date: May 15, 2017 Location: Iowa Posts: 1,098	As someone who likes to jump on anything new in AR, I resisted going gas operated, did a lot of research, and concluded I didn't need gas piston. Yet, I still have a Superlative Arms piston conversion sitting in the parts bin, waiting for ?. With the SA unit, you can use your stock upper receiver but you have to use their bolt carrier and gas block. I built a 7.62x39 AR, direct impingement, using a KAK Industries barrel and bolt, on sale, and magazines made for 7.62x39. I probably have $300 in the whole upper. Shoots great, by the way.

November 23, 2020, 10:32 PM	#11
MGMorden Senior Member Join Date: April 3, 2006 Posts: 158	The accuracy guarantee won't likely be in place after you switch - piston driven guns tend to be a little less accurate than DI (more moving parts jostling the gun around). Also, a piston driven system isn't really just swapping a few parts - you're changing out the entire gas system and will likely also need a new upper, handguard, etc. IMHO, if you're doing a piston-driven gun start it out that way - don't start with DI and then try to back into a piston driven setup. Or better yet - get a different rifle design. AR-15's are DI guns and 99% of all the parts out there are geared that way. Once you step into piston driven systems there is no mil-spec to follow anymore - it's all proprietary.

January 2, 2021, 08:18 PM	#16
Super Sneaky Steve Senior Member Join Date: August 9, 2011 Posts: 1,250	Everyone has an opinion I guess, but few actually answered the OP. https://www.blackriflearms.com/ I prefer piston guns. They are great for many reasons. One of which is they are easy to clean if you shoot cast boolits. I wanted an 80% gun in 762x39 and it's much easier for me to mill an AR lower than to do an AK build. So far my BRA upper has been perfect with C Products mags. If you want a piston get one. Don't buy a gun to please other people.

January 5, 2021, 01:19 AM	#17
Ignition Override Senior Member Join Date: February 18, 2008 Location: About 20 nm from the Big Muddy Posts: 2,884	Super Sneaky Steve: "If you want a piston get one. Don't buy a gun to please other people". Perfect philosophy in a nutshell. My choice in 7.62x39 guns (three imported AKMs plus an imported Czechpoint VZ-58) wouldn't please many people here, as if it should matter one bit. Interesting how the cheaper Russian ammo - in the right gun with an AR's aperture or red/green dot sights etc - can be a different animal. Last edited by Ignition Override; January 5, 2021 at 01:25 AM.