Custom barrel for 7.62x39mm for a semi-auto

BeaverMeat

BeaverMeat

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Here comes an other crazy idea built upon my knowledge, and lack there of when it comes to practical experience with the .39 cartridge.

I feel the need to reinvent the wheel. I think it stems from my "I have something that no one else has" mentality. Because, why would you want something that everyone else has? I may be out in left field, so convince me that I'm on crack.

I am wanting to put a custom barrel on either an SKS or 858. I want to have a rifle twist of 1:7.5 to use heavier 150 maximum grain bullets as I intend to deer hunt with this rifle. Second, I am looking for a barrel length of 542mm (21-5/16" or 21-3/8"). The reasoning for this ideological barrel length comes from hours of study of accuracy comparisons from other shooter's experience. The barrel length of choice stems from the Zastava M72 and Tabuk DMR. Just the right length to add a small boost in muzzle velocity. The barrel length is not definite, but I want harness as much power for the heavier bullet so it does not instantly drop like a rock. And yes, I am aware of the .39 ballistic qualities. I am not hoping for a match grade or 1000m precision rifle here.

With that said, what platform to use? SKS, or 858? And who will do the work? I can attempt it myself, but I lack the tools and workspace... and it would probably take me two rifles to get it done properly.

Personally I want to use the 858. Yes, the SKS is cheaper and the receiver is threaded, but the 858 has a superior action. So who gunsmiths 858s? Would this be worth the cost? (probably not, but it would be unique)
 
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Haven't considered it for x39 but x54 I've really though about it..........oh what I would do tho to have a left handed bolt action shooting 54R........
 
Worth the cost you ask?

As for the 858, it would be a great way to make a $200 dollar rifle that sells for $800 end up costing you probably $2000 lol

It very effectively shoots within that 8"x12" square up to 300 meters.

What are your intended goals as far as accuracy goes? I would assume that's what you're driving at with this whole thing?

You might drop the sickening amount of cash only to find out that......it still shoots like a cheap frankensteined Czech surplus rifle.

Have you even tried a heavier projectile 7.62 x 39mm in a standard CZ858 yet?
 
tiriaq said:
Why would a 1:7.5" barrel be needed to shoot bullets to 150gr?
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I have read from a Russian source that during testing, it was found that a bullet under 140 grain performed well with a 1:9.45, as over 140 grain projectiles benefited from a 1:7.5 twist.

Travis Bickle said:
Worth the cost you ask?

As for the 858, it would be a great way to make a $200 dollar rifle that sells for $800 end up costing you probably $2000 lol

It very effectively shoots within that 8"x12" square up to 300 meters.

What are your intended goals as far as accuracy goes? I would assume that's what you're driving at with this whole thing?

You might drop the sickening amount of cash only to find out that......it still shoots like a cheap frankensteined Czech surplus rifle.

Have you even tried a heavier projectile 7.62 x 39mm in a standard CZ858 yet?
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I would buy second hand, and I am aware of the costs associated. My goal is to push the envelope of the .39 rounds effectiveness past the 300m mark. Like I said, a semi-auto deer rifle with a little more power and accuracy. And no, I do not have an 858 yet. Been wanting to buy one but have not thrown down the money yet. I know, it is a cracked out idea. I have also never shot a rifle with a .39 caliber.

With that said, my next option is to just get a surplus M72 or RPK barrel and profile it to fit.

Most likely this is all talk and I will buy a 858-2 and leave it at that.

:onCrack:
 
I installed a 1-13" twist Shilen barrel on my 788. It shoots 168grs Sierra bullets very well.
If you really want to push the 7.62x39 envelope do it in a bolt action with a match reamer. I have a match reamer on order, but my intention is for short range BR, not long range.
An SKS or 858 with a match heavy barrel only ends up being a little more accurate for a substantial cost with diminishing returns. I own a stock 858 and wouldn't change a thing. It's very accurate for it's design.
 
The only quick twist .30 barrels are some intended for long range shooting, using 240gr VLDs, and those destined for low velocity use with 220s.
For over a century, 1-10, 1-12 barrels have successfully used .30 bullets with a wide range of weights.
 
The stock barrel is 1;10. This will stabilize a conventional (non VLD) bullet up to 200 gr.

I made a 20" bolt rifle in 7.62x39 using an old 308 match barrel in 1:13. It shoots 175 gr bullets well.

I suggest you use a 308 barrel for your project. barrels are cheap and lot more bullets to chose from. Just make sure the chamber has a deep throat to take the heavier bullets.

Add 2" to your 858 will add about 50 fps. This makes no real difference to trajectory or terminal ballistics.

I used to hunt with a Mini 30. I pulled the FMJ bullets and seated a 150 gr Round nose (this is a shorter bullet than a spitzer). It worked well.
 
lejarretnoir said:
I installed a 1-13" twist Shilen barrel on my 788. It shoots 168grs Sierra bullets very well.
If you really want to push the 7.62x39 envelope do it in a bolt action with a match reamer. I have a match reamer on order, but my intention is for short range BR, not long range.
An SKS or 858 with a match heavy barrel only ends up being a little more accurate for a substantial cost with diminishing returns. I own a stock 858 and wouldn't change a thing. It's very accurate for it's design.
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I have read that a slower twist of 1:14 at a minimum is the way to go; according the the Greenhill equation. I know of Colt ARs that have been chambered for the .39 have a twist of 1:13 and seem to shoot incredibly well. I haven't fully deiced what I exactly want as most of my knowledge I have obtained reflects military applications and match grade shooting.

I know bolt-action is the way too go for accuracy, but I want a semi-auto. Because all I have is bolt-actions and one Rem 760 pump for hunting purposes. I am looking for a deer/target rifle that is absurdly different then most. Basic hunting rifles just don't blow my hair back.

Ganderite said:
The stock barrel is 1;10. This will stabilize a conventional (non VLD) bullet up to 200 gr.

I made a 20" bolt rifle in 7.62x39 using an old 308 match barrel in 1:13. It shoots 175 gr bullets well.

I suggest you use a 308 barrel for your project. barrels are cheap and lot more bullets to chose from. Just make sure the chamber has a deep throat to take the heavier bullets.

Add 2" to your 858 will add about 50 fps. This makes no real difference to trajectory or terminal ballistics.

I used to hunt with a Mini 30. I pulled the FMJ bullets and seated a 150 gr Round nose (this is a shorter bullet than a spitzer). It worked well.
Click to expand...

I have thought about using a .308 barrel, but I don't want to rely on hand loads. And if I am going that far I might as well re-chamber it for a .308, or just buy a M1A. I want to use the .39 for common ammo reasons and cheap ammo... for now. I will have to do some further research in to rifle twist. I really boils down to availability and cost.

The SKS was my first choice for this particular project, but I have other plans for an SKS. I am bound to the 858 for the better action. As I have never had an in-depth look at a 858, would it be possible to thread the receiver instead of pinning on the new barrel? To my knowledge using the pinned fastening will lower the cost, correct?

There are still too many options and variables to consider. Custom made barrel, or custom fitted barrel. My first choice was to install a old-new stock RPK barrel then re-profile and shorten to desired length. Trade custom twist for chrome.

Thanks for the input guys.
 
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You missed the point about using a 308 barrel. the milsrp ammo works just fine it it. The reamer includes the correct throat.

Before you go very far with this, speak to some gunsmiths about changing the 858 barrel. If it is a press-fit he might need a press to remove or install the new barrel. Some smiths might not want to do this.
 
you keep referring to the 7.62X39 as a .39... and even a .39 "caliber"... this clearly shows a lack of understanding and renders this project suspect... the 39mm refers to the case not the caliber... the 7.62 transaltes to a .309" - .311" bore or caliber... so you might refer to this as a .31 but certainly not a .39.

As for rebarreling an SKS... its your money, but I view that as a waste... there are many better platforms for a custom barrel job... for no more money and probably less... maybe alot less. A real cool way to go with the build would be to chamber to 7.62X39 but bore to .308", this would open up a whole new world of reloading options... why not consider a bolt option??? On a 700 or Mauser action.
 
BeaverMeat said:
I have read that a slower twist of 1:14 at a minimum is the way to go; according the the Greenhill equation. I know of Colt ARs that have been chambered for the .39 have a twist of 1:13 and seem to shoot incredibly well. I haven't fully deiced what I exactly want as most of my knowledge I have obtained reflects military applications and match grade shooting.

I know bolt-action is the way too go for accuracy, but I want a semi-auto. Because all I have is bolt-actions and one Rem 760 pump for hunting purposes. I am looking for a deer/target rifle that is absurdly different then most. Basic hunting rifles just don't blow my hair back.



I have thought about using a .308 barrel, but I don't want to rely on hand loads. And if I am going that far I might as well re-chamber it for a .308, or just buy a M1A. I want to use the .39 for common ammo reasons and cheap ammo... for now. I will have to do some further research in to rifle twist. I really boils down to availability and cost.

The SKS was my first choice for this particular project, but I have other plans for an SKS. I am bound to the 858 for the better action. As I have never had an in-depth look at a 858, would it be possible to thread the receiver instead of pinning on the new barrel? To my knowledge using the pinned fastening will lower the cost, correct?

There are still too many options and variables to consider. Custom made barrel, or custom fitted barrel. My first choice was to install a old-new stock RPK barrel then re-profile and shorten to desired length. Trade custom twist for chrome.

Thanks for the input guys.
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Sounds like you are working your way down to buying a .308... which is what you should do rather than throw money at this project.
 
I think Dlask did a few 858's into match barrels. Not sure if he bored out the original barrel and threaded or press fitted it in.
Give him a call. I believe he's a dealer here under the name Dead Zombies.
 
hoytcanon said:
you keep referring to the 7.62X39 as a .39... and even a .39 "caliber"... this clearly shows a lack of understanding and renders this project suspect... the 39mm refers to the case not the caliber... the 7.62 transaltes to a .309" - .311" bore or caliber... so you might refer to this as a .31 but certainly not a .39.
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I understand that... x39 is what I meant. Sorry, I don't talk guns all day and everyday. I know the differences between a "3-line" and a .308. Ballistics knowledge is my only weak point when it comes to guns. As you can see others did not find it necessary to belittle my intelligence by pointing out a simple flaw in my typing. I my be erratic or eccentric, but not stupid.

I am not re-barreling an SKS. I will be doing a few simple tweaks, but not a new barrel. As I said before I don't want a bolt-action as I am not attempting to create a match grade gun here. I don't think you read the complete post.

and yes, I might be talking myself into a .308, but If I wanted a .308, I would get a .308. It was the NATO round, it is obviously been tweaked relentlessly, the knowledge is out there, it has been done before (in the West) no challenge or uniqueness. Really I do want a M1A which is very excellent right from factory. And I do not want a cheap Chinese copy. (fyi, I do not consider a Chinese SKS a copy. It is a co-op build) I am looking for something unique. A Russian type rifle that strays from the standardized Russian method of firearms production. All Russian "3-line" barrels are of the exact bore and twist no matter the weapon. It is standardized for production. Be it Mosin–Nagant, SVT-38/40, SKS, AK-47, SVD, RPK, DP, RPD, PPsh, and TT-33. They all have the same rifling that was found to be efficient enough in all lengths and projectiles. With a few exceptions of course.

Ganderite said:
You missed the point about using a 308 barrel. the milsrp ammo works just fine it it. The reamer includes the correct throat.

Before you go very far with this, speak to some gunsmiths about changing the 858 barrel. If it is a press-fit he might need a press to remove or install the new barrel. Some smiths might not want to do this.
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I have read of both negative and positives to this. It seems that people who have not used this method always say no. I will look into it further. I have to absorb all the information I can first before I make am "educated" decision. But I am now convinced that a slower twist is the way to go as I am choosing a longer barrel length.
 
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