SKS in .357 Magnum

[LAGS]

In another thread, I had mentioned about making an SKS into a .357 Magnum.
Well, lets start off by looking at the design factors in converting a rifle to another caliber.
First.
Is the chamber pressure near or within the design limits of the original cartridge ?
Second
Is the bolt length of stroke or action length around the same length or less than the new cartridge ?
Third
Is the length of the magazine compatable with the length of the new cartridge ?
Fourth
Is the Bolt Face of the original Cartridge compatable or able to be modified to fit the new Cartridge ?
Fifth
Is the case Diameter the same size or less then the original cartridge ?
Sixth
Is the Bore diameter the same as the original Caliber, or will the Barrel have to be totally replaced to work with the new caliber, or can it be Re Bored to the new caliber ?


So far, what I have found is all the factors point in a positive direction.
Granted, the barrel will have to be Replaced and would probably be too thin if rebored from .311 to .357

Then you get into the other factors like, what will it take to get a barrel blank to fit the receiver.
Will the increased diameter of the barrel effect things like , can the original sights or in this case the Gas Block or gas piston be used, or would new ones need to be made or modified ?

Take a look at all the things that I mentioned, and post your opinions.

One other factor I did not mention.
The Cost ?
But to me, the cost is secondary.
Not that I am made of money, or have all the tools to complete the project In House.
But I love having things that are different, or unique.

[armoredman]

Now THIS is gonna be fun to watch!

[308Jeff]

This would be one of the neatest things ever.

How will you get the rimmed cases to feed from a magazine?

[rancher1913]

if you get this to work I want one. good luck and would love to see photos, going to watch this closely.

[LAGS]

First Question was about getting the Rimmed rounds to feed out of the magazine.
Well a Takorov does it, so does a Desert Eagle, the Mosin Nagant, the Smith and Wesson Model 52 and the SMLE.
That is just a issue that has to be dealt with, but not insurmountable.
But in another thread, it was suggested that it be adapted to use a Desert Eagle Magazine.
That is a good Idea.
Now this thread is more about Kicking around Ideas to see if it is possible to do the rifle.
Currently I have a ton of projects in the works, and I left my Lathe and Mill in California.
So any machinging I would have to farm out or borrow someone elses equipment to do the build.
But I hope I can inspire others to do a build on their own since so many like the idea.
But lets talk it thru and see if it is truely feasable.

[LAGS]

Now answer the Question,
Why do others think this is a desireable rifle.
The SKS is a great rifle.
Handy, cheap to shoot, fairly accurate and plenty of power.
Why Change it ?

[samari46]

Do a google search for the 9mmx39 cartridge. Think there is one that would take a standard chambering reamer and no worries regarding trying to mess with a rimmed cartridge. Just a barrel swap. Sounds easy but you do have to do the gas port hole for the semi auto function. Frank

[rondog]

Now answer the Question,
Why do others think this is a desireable rifle.
The SKS is a great rifle.
Handy, cheap to shoot, fairly accurate and plenty of power.
Why Change it ?

That would be my question. I don't have an SKS, never shot one, but a .357 autoloader would be cool. Just not sure that's the rifle for it. I AM harboring a serious lust for a .357 levergun though, and a local guy is selling one. Just have this miserable old woman standing in the way.....

[LAGS]

@ rondog
My Old woman has her own 30-30 when I met her, it had been her late husbands.
But she liked my Marlin .357 better and wanted it.
So I bought he a Henry .357 in the Steel Blued Finish.
But now she too thinks the Semi Auto would be fun.
She told me, I know you can build one.
You are so smart, MacGyver wants to be you.
And Yes, she really said that.

[GhostHawk]

And I agree with her, I think she's right.

I think your both smarter than MyGyver.

And I think an SKS that would handle .38 specials and .357's would be an awesome rifle. Keep the speed around 1200 fps, no need for gas checks, good penetration with range scrap. And probably still get good expansion. A primer, 4-5 grains of powder and a couple of cents for lead. It is going to put you under a dime a round. .38 special brass is easy to find and fairly cheap.

Yeah, cool project.

[LAGS]

@ samari46
There are probably a dozen cartridges that would be better or easier to convert this rifle too.
But the challange was thrown out about making it into a .357 Mag .
Make it a Common Caliber, and it would be great if it could fire the .38 Specials also.
@ ghosthawk
The cast loads would be great.
But if the conversion would be made, it must be safe and regulated with any standard over the counter factory loads.
But it might be able to cycle with the cast loads and the same gas port size.
If not, then you might have to make an Adjustable Gas System .

[jmorris]

Replaced and would probably be too thin if rebored from .311 to .357

Not to mention wouldn't be very accurate at distance without rifling.

Bore diameter will be closer to .350 for a 357 but you are likely not going to be able to rifle the barrel yourself any way. The 357 operates at around 10,000 psi lower pressures than the 7.62x39 so there might be enough diameter there to bore and install a barrel liner.

https://www.gunpartscorp.com/ad/594260.htm

Then you just have to figure out how to reliably feed rimmed cases.

It would be a lot less work to set it up as a 9x39 and down load it.
https://en.m.wikipedia.org/wiki/9×39mm

[LAGS]

I think the thing people would like about this conversion would be having a common Factory cartridge.
The SKS action is not that all refined to justify going to a Custom Round or being able to only shoot a Downloaded version of a Good Round
But a barrel could be turned out of a .357 barrels Blank with much less effort than to try an sleeve a already thin barrel.
Or to rebore and refile the original barrel.
The breaching can be set up as the pinned attachment as the SKS is now.
Or the receiver could be threaded and the barrel shank be threaded for a more positive set up.

[LAGS]

Years ago I had a 30 Carbine in the .256 Winchester , I think they called it a Ferret.
That round was made from a necked down .357 magnum case.
I remember it fed the rimmed round out of the Magazine just fine.
But a 30 Carbine I don't think would handle a magnum pressure and the barrel is too thin to go out to .357 groove diameter
You would also have to find a Ferret bolt to fit the cartridge head or modify the existing bolt face for the rimmed cartridge.
When I get home from my Real Job.
I may start playing with the numbers on the SKS and see how it looks

[lar45]

Some SKS's have a threaded barrel. I think the Russian ones were threaded and some of the China ones were also.
This might be easier to work with instead of setting a press up to press the barrel out to work on it.

[LAGS]

That was my thinking also.
So if your receiver has a threaded barrel then all you have to do is thread the new Barrel shank to match the receiver.
But I have a Cheap Chinese POC that has a pressed in barrel.
So , either stay with a pressed in barrel or thread the receiver.
Or heck , for real custom make a take down barrel for it.
I had a Japanese 99 with a take down barrel that was original.

[Moleman-]

Great project! Looking forward to seeing it. One thing you may want to look at is the pressure curve per inch of barrel on the 7.62x39 and 357mag. Note what the Port pressure is on the SKS as you'll likely have to move the gas block back some to match up closely to where that some pressure is on the 357Mag barrel. You might also have to open up the gas port. Even if you start off with the same pressure the larger bore and straight walled case will loose it much faster. Haven't made an SKS barrel , but pressed in are much easer to make for an AK even though I prefer making threaded ones. You'll likely need to use a press of some sort to populate either barrel.

[LAGS]

To tell you the truth, I have never removed a barrel from an SKS or AK.
So the pressed in set up will be a new adventure for me.
And Thanks for the tip on the pressure curve.
Most of my work has been on bolt actions or single shots.
But I have removed barrels that were pressed in, but they were 22s
This is why I am asking others with experience with this type of action for pointers.

[armoredman]

An SKS in .357 Mag that takes DE magazines, the weirdest of the pistol caliber carbines, but the most interesting!
Concept art - forgive my horrible editing.

[LAGS]

Your Concept Art looks interesting.
I think the magazine looks about 1/2" too far forward, but gives the impression of what it could look like.