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S12 SBS Questions

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Hello everyone,

 

Does anyone on here have experience with converting the S12 into a NFA SBS?

 

I am well familiar with NFA process but what I am looking for is the process on getting the actual S12 into SBS config.

 

The S12 i am dealing with has an 18" barrel, completely unmolested, still in the wrapper in sporting mode.

 

Questions:

 

1- How short can the barrel be cut before running into issues?

2- What are those issues?

3- I realize gas plug will need help but whats recommended?

4- Besides the usual trigger and stock job, what other internal parts need to be changed?

 

I tried searching the forums and came up empty, my apologies if this has been covered.

 

Thanks

 

 

 

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1: 12" assuming you bought a stamp, etc.

2: Basic issues is that shortening things up means that the gun is not operating in the middle of the wide gas burn window. So you tend to need to make the gun run either hot or mild ammo, but not both. Getting it to run both is a lot more work. If you simply chopped the barrel and enlarged the ports, you can expect to only run very hot loads reliably. Also to need to clean your gas block more.

 

Any chop will likely require increased port size. 12" is the shortest you can go before you pretty much need to weld up the ports, hone the barrel and move the gas block closer to the bolt face. That part is much more appropriate to leave to a shop that specializes in S12 SBS conversions, but a few more skilled DIY people have built functional guns

3: The plug needs nothing. It adjusts a gun that is already running. Once you have a gun that runs, you can consider a plug with more settings or an auto plug. None of those will give you functionality you don't already have.

4: Internal? Just the shortened piston and gas tube, if you consider that part internal. There's room to improve the bolt shape, and possibly extend the barrel shroud depending on when your gun was made, but these aren't absolutely necessary.  Probably some rivets if you have pressed out the barrel to do the short gas modifications and port moving.

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1: 12" assuming you bought a stamp, etc.

2: Basic issues is that shortening things up means that the gun is not operating in the middle of the wide gas burn window. So you tend to need to make the gun run either hot or mild ammo, but not both. Getting it to run both is a lot more work. If you simply chopped the barrel and enlarged the ports, you can expect to only run very hot loads reliably. Also to need to clean your gas block more.

 

Any chop will likely require increased port size. 12" is the shortest you can go before you pretty much need to weld up the ports, hone the barrel and move the gas block closer to the bolt face. That part is much more appropriate to leave to a shop that specializes in S12 SBS conversions, but a few more skilled DIY people have built functional guns

3: The plug needs nothing. It adjusts a gun that is already running. Once you have a gun that runs, you can consider a plug with more settings or an auto plug. None of those will give you functionality you don't already have.

4: Internal? Just the shortened piston and gas tube, if you consider that part internal. There's room to improve the bolt shape, and possibly extend the barrel shroud depending on when your gun was made, but these aren't absolutely necessary.  Probably some rivets if you have pressed out the barrel to do the short gas modifications and port moving.

 

 

Thank you for your response.

 

#1 I like to do research as to feasibility b4 spending $200 in a pipe dream.  if i feel there is way too many factors that could go wrong then it wont happen. Spending $1500 + the gun at tromix or anyone else is not something i am willing to do for a thrill at the range.

 

 

#4 extend barrel shroud depending when the gun was made?  can you tell me what year or so? i know how to read the stamping.

 

 

 

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In post two, I showed you how to search using google. I should have said "extended barrel hood.' search for that, and the threads you find will answer your questions. You go by what your gun actually has rather than serial ranges.

 

Your serials on the left side have two digits which correspond to its year of manufacture. They should be fairly obvious.

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I suggest you do a lot of searching through existing threads and either have someone like Cobra https://www.facebook.com/Cobras-Custom-LLC-595137240541168/ or evolutions llc do a basic bolt carrier service and shoot your gun a lot before you jump off the deep end. If you aren't satisfied with the function you can get in full length, you are going to be very unhappy if you complicate things further. If on the other hand, you are happy with your gun's performance,and are willing to take the risk that you can only run hotter ammo after a chop, You'll have the friction work done for a 12" chop, and probably would only need a trust, stamp, and to remove the block and increase the port size, then re-install.

 

You have $6-900 in this gun already. No need to get in a hurry and throw that away.

 

If you were to change your mind about professional work, I think you would be happy with the SBS services offered by tromix, tac47, lonestar, evolutionz. I would never have a local gunsmith do work on a saiga 12. I've seen too many people here with guns that otherwise competent local smiths messed up.

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I went through this process last year with my S-12.  I did all of the work myself.  A search of this forum suggested that as long as the barrel was cut no shorter than 13 to 14 inches, that the gun should still function with the factory length gas system.  But it may have trouble with lower powered ammo at that length.  Since my gun was already a little undergassed from the factory, when I cut the barrel to 14 inches, I also removed the gas block, drilled a 4th gas port, and increased the size of all the existing ports slightly.   I was rewarded for this effort with a gun that runs better on the low end of ammo than it did before the barrel was shortened.  Light trap loads that were previously iffy, are now reliable through my shotgun, even out of the drum.  The downside to this is that it will foul the gas system more quickly, and require more frequent cleaning.  Shotgun ammo is dirty, and there is unfortunately no free lunch.

 

I am running a 5 position gas plug, but you must realize that none of the aftermarket gas plugs will compensate for an undergassed gun, so if you have function problems as a result of chopping the barrel, the aftermarket plug by itself will not help you.  They are designed to take control of an overgassed gun, and also provide a more precise adjustment so you can better adjust for specific ammo than you can with the factory 2 position plug.  Before going SBS, my 19" gun with the 5 position plug would not function with ANY ammo on positions 1 or 2.  It would work with 3" magnums and some heavy 2-3/4" loads on position 3.  Positions 4 and 5 worked with some lower power loads.  After the mods, I still can't use position 1, but 3" magnums will now cycle the gun on position 2.  So I gained a little function on the low end, but if I went back to the factory gas plug, my shotgun might be a little overgassed now.  I am satisfied with its performance as is, so I have no plans to increase the gas port size any further even though position 1 of the plug is still not usable.  I just keep in mind that it is designed to gain control of an OVER gassed gun, and that I don't want to overgas my gun.

 

As for your 4th question, to the best of my recollection, all of the work I did specifically related to making it into an SBS was forward of the trunnion, other than stamping the receiver with my trust information.  A lot of guys will recommend a full profiling of the bolt, but I did not really find that to be necessary.  When I first got the shotgun several years ago, I did some polishing of the bolt, carrier, and the upper surface of the hammer, and that really smoothed up the action when cycling by hand.  I used power tools, but still I tried not to get too aggressive.  Everybody who has handled my shotgun has commented on how smooth it operates.  Some people will tell you that you need a full profile job to seat a full mag against the closed bolt, but in reality it is more a matter of correct technique and practice, than any other factor.  Watch GunFun's video on how to do it right.

 

s12-11.jpg

 

Edit to add;  I know you are leery of investing in a $200 stamp at this stage in the game, but given that you are looking at a 4-5 month wait no matter what, and if you are filing as a trust they will be making that more of a pain in the ass when the new rule goes into effect in 6 months or so, I would go ahead and file NOW to beat the changes, and to get your application in process.  If you later decide NOT to go SBS, you can return the approved form and stamp, AS LONG AS YOU HAVE NOT MADE THE FIREARM IN QUESTION, and get your $200 refunded by the ATF.

 

Edited by Netpackrat
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I'm in the process of SBS'ing one of my S-12s and transforming it also into an AK wood furniture variation (will post photos of the finished product in a few months).  I have my stamp and I've chopped the barrel to 12".  Based on reading the "SBS Technical Info Thread" in the NFA section and particularly the post there by C&S Metall Werkes (http://forum.saiga-12.com/index.php?/topic/38318-sbs-technical-info-thread/?p=597096) I added 2 ports to my factory 4 and opened the opening in the gas block a bit to expose the extra ports.  I left the factory ports alone at approx .078" and made the two extra ports also approx. .078" although due to a slight slip up on my part one of them is closer to .082

I've done nothing else to the gun and was able to fire some test rounds today.  I had the factory 2 position gas plug set at 2 (wide open) and it cycled the only target load I had available to me at the moment just fine.  These were Winchester AA #8 shot listed as being 1200fps.  I ran two 10 round mags through and all rounds fed, fired, and ejected with authority.   Now on to the rest of the project . . . .  biggrin.png

 

Edit to add . . . The gun I started with is one of these RWC IZ109T

RWC%20Saiga-12%202_zpsvlc77ym4.jpg

Edited by yamadog35
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