Can you take the patrol rifle and have someone cut the barrel or switch it out with the 10 inch barrel? Can you just buy a classic lower and add a swat pistol upper? Do they just sell the upper and lower? Or how can I get a smith to add a stock to the pistol?
I am not a gunsmith and dont want to do the work myself. Not sure what the best way to get an SBR sig with a folding stock is…
Alfred,
Welcome to the board!
In the future you would probably have much better luck in getting a response if you posted this question in either the NFA forum (since an SBR is an NFA Firearm) or in the Other Assault Rifles forum (since the Sig is not an AR).
Perhaps a Moderator would be nice enough to move this thread there for you!
I’ve never seen Sig uppers or lowers sold individually but that doesn’t mean they aren’t available.
Good luck in your project!
-RD62
get one of the pistols and add a M4 stock and buffer tube… That would be something you could do your self…
You might want to ask SHIVAN, as he put one together that is now for sale in the EE.
https://www.m4carbine.net/showthread.php?p=557598#post557598
They sell the SWAT pistols for about $1700, and adding a stock is super simple.
The end cap has two holes in it, I just fashioned a tool out of two allen wrenches locked in a visegrip pliers and twisted it right off.
You screw the AR receiver extension (buffer tube) in and add the AR stock.
The swap took about 10 minutes, most of it was getting the spacing and tension just right for the “tool” I used to get the end cap off. NOT a gunsmith or armorer job at all. Anyone who can take an M4 stock and receiver extension off could handle it.
Are you able to mount a stock that folds and collapses like that? I would like to mount the mag pull or the sig factory style folder. How much is the receiver extension and other parts? Do I have to weld or grind anything? Can I possible mess up anything mechanical? Is the end cap made to come off or do you have to break it off?
I could of grabbed a SWAT pistol at a gun show for 1400 yesterday… Do they have generations of the 556 pistol that have different end caps? I heard they changed it so that its harder to SBR them now.
SIG carbines have the serial on the upper, not the lower like AR15’s.
Meaning, SBRing can be a big pain in the ass if you already own a SIG carbine.
If you dont own a SIG carbine, get the 556 pistol and go from there.
i just did the same thing as shivan. had a sig 556 pistol. once the paper cleared and all was legal, threw on an m4 tube and stock, just the way he explained it. it took maybe 15 minutes. easiest way to do it i think.
There are some guys who mounted folders, and I think Sig is selling them now, but I just used the AR receiver extension, and an AR stock. It depends on the quality you pick, but a set would probably run you anywhere from $50 to $200. No welding or grinding that I know of, but if they changed it as you say below, I’ve got no idea. I don’t think they did to be honest.
The endcap is screwed in, and should come right out.
I could of grabbed a SWAT pistol at a gun show for 1400 yesterday… Do they have generations of the 556 pistol that have different end caps? I heard they changed it so that its harder to SBR them now.
They have the version I have, and then they have Classic carbines which are a little different on the lower triggerguard and magwell area, but they look the same at the stock interface.
If you can change a tire, you can change the Sig pistol in to an SBR when the form comes back.
Would it be as easy to mount a folder. I cant see spending the money if its not a folder as I have an NFA SBR colt and am only interested in this becuase it would fold smaller. How accuret are these? How many meters can you shoot them?
Unfortunately, you can’t just take a Sig556 Patrol Rifle and cut the barrel. As you can see from the below picture, the barrel is thin and then gets larger to accept the flash hider diameter.
I like many of the features of the Sig556, but it’s a heavy rifle. An SBR would be ideal, but those selling the factory SBR’s seem to think they’re made of gold. Since Sig has the $300 rebate thing going on Sig556 rifles, I’m still debating about what to do.
there are several choices in folding stocks for the sig.agp arms just came out with a new folder that works with the sig,i think spike’s carries them.if you want to stay with m4 style stocks ace makes some durable folding units.adding a stock to a 556 pistol is really pretty easy,don’t sweat it.
one thing to think about is what type of sling you’ll be running and make sure it will work with the stock you go with.i went with the ace folder because it let me run a magpul asap plate and ms2 sling on the gun no matter if the stock is folded or deployed.
If you want the Swiss type side folder on the SBR you have another option.
Purchase 556 pistol,
Purchase 556 “classic” rifle with Swiss side folder,
Swap lowers once approved (30 second SBR),
Mount receiver extension and suitable AR stock on the full size rifle (I like the UBR on the 556),
Sell or keep the full size rifle.
That would be a good option, but the pistol uppers that I have seen are marked “For Pistol Use Only” or something like that. It’s only cosmetic, but that makes the use of a Sig556 pistol a no go for me.
the -pistol use only- marking can easily be filled and refinished 
Could I just mount a factory sig side folder on the pistol? How much would it be for the parts other than the stock?
the factory sig side folder with the plastic "buffer tube " are problematic,and they’re commercial sized 
Look at it this way- Practically anything that says “Commercial” is going to be cheaper if you go with magpul.
Just buy a factory made sbr from Wild West Guns in Anchorage, Alaska. I believe they have them in stock.
Yeah, and it still needs to go through his CL3, and he still needs a stamp.
I think he’s trying to do the same smart thing I did and avoid CL3 all together.