View Full Version : Anyone SBR a Sig 556 pistol?

February 7, 2009, 02:44 PM
I just picked up a new Sig 556 pistol and I want to SBR it. I have been through the process once with an AR, so I feel pretty comfortable as for what to do (regarding ATF Form 1). Just wondering what stock you all have put on this weapon. I'm leaning toward the Magpul UBR, but I'm just not sure if that would be the best choice. I don't really want a Sig side-folder. I would appreciate any input on this subject. Also, if anyone out there has put a Magpul UBR on a Sig 556 pistol, could you give me the overall weapon length with stock extended (not counting flash hider) for my form 1. Thanks!

February 9, 2009, 11:05 PM
For Pete's sake, WHY ! ! ! ?

February 10, 2009, 04:14 PM
uhm, because it's as close as I'll ever get to a Sig 552?

February 10, 2009, 04:17 PM
We have done several but none with the stock you mention

WildnicegunAlaska ™

February 10, 2009, 06:20 PM
No one should ever ask "why" in a gun forum. Sounds a lot like politicians asking us why we "need" something. The guy wants to SBR a 556 pistol because it would be a cool thing to do. No other reason is necessary.

Now, back to topic.. I have seen a few 556s converted in the last few months. They look great but they have all been side folding stocks. In my opinion, the side folding stock is the best thing the platform has going for it.

February 10, 2009, 09:19 PM
I decided to go with the Magpul UBR for my stock. In the end, just couldn't go with a side-folder. I know the UBR is heavy, but the 556 pistol is front heavy, so maybe it will balance it out. To be honest, I just thought the UBR looked cool.

February 11, 2009, 10:23 PM
I completely understand why you went with the UBR for a 556 pistol SBR conversion. So... show us a pic or two!

February 11, 2009, 11:41 PM
With regard to pics, give me about 90 days. Just dropped my Form 1 in the mail on Monday. Needed to pick a stock so I could figure overall length for said form. Of course, after I get my stamp, I'll then have to find a UBR. Saw one on e-bay for about $400. Hopefully I can find one at a decent price when the time comes.

April 23, 2009, 10:04 PM
I recieved my stamp on March 30th. I submitted the form 1 on Dec. 6th.

April 24, 2009, 10:38 AM
That looks great!

April 26, 2009, 10:54 AM
Great looking gun! I have always secretly wanted one of those. If you don't mind me asking, where did you pick yours up?

And I really like this:
No one should ever ask "why" in a gun forum. Sounds a lot like politicians asking us why we "need" something.

True words. Very true.

April 26, 2009, 11:24 AM
Wow, thats a very nice looking rifle. Dang it, another thing to add to the "when I get rich and famous" list... Hows it shoot?

April 27, 2009, 04:25 AM
received my stamp back at the end of march :cool:

still waiting on the troy rail and a few other parts to finish it up :(

the ubr balances out the 556 nicely and fits the lines of the receiver pretty good.as soon as my ace folder gets here i'll be trying a ctr on it,if i like the folder i'll have a ubr for sale in the near future ;)

gratuitous pics now :D



Willie Lowman
April 27, 2009, 10:53 AM
Now why did you have to do that to me? I promised my self I wouldn't buy any new rifles this year and you have to twist my arm and make me buy a Sig 556 pistol to SBR. Thanks jerk! Why are you making me do this?:);)

May 13, 2009, 02:42 PM
Newbie here. Question on the stock, is that the folder kit from SIG. Thanks...


May 14, 2009, 01:10 AM
That is just begging for you to put a can on it.

Tucker 1371
May 14, 2009, 02:31 AM
I agree with Yellow, a can would finish that rifle up nicely

Newbie here. Question on the stock, is that the folder kit from SIG. Thanks...


Negative G2, that's a UBR stock from MagPul

May 15, 2009, 12:28 AM
Thanks Tiger-Mule for the info. That's the way I'm headed.


May 21, 2009, 07:36 PM
Found out my Form 1 was approved today (5/21/09)! Now just have to wait anxiously by the mail box.

May 22, 2009, 07:00 AM
That pair of SBRs is beautiful. The AR is a 10.5", yes? What brand?

May 28, 2009, 11:44 AM
I have SBR'd a 556 pistol and used the CTR stock.

May 30, 2009, 03:58 PM
thank you :cool:

the ar is a tactical innovations lower and lmt 10.5 upper.

i've also removed the ubr from the sig and replaced it with an ace folder and ctr.still waiting on the troy rail and a front sight.

and here is a pic of my .50 beo sbr :)





June 28, 2009, 06:52 PM
Brand new to this. I have questions about putting a folding stock on a Sig 556 pistol.:confused:

May 25, 2010, 05:16 PM
Yes...I'm looking to do the same thing to the 556 pistol. In fact, in addition to the folding stock, I'd like to throw on a quad rail so I can attach a vertical grip. Basically, I want to turn this thing into a bullpup carbine...is that too much to ask?? By the way, does anyone know if the barrel is threaded after taking off the muzzle brake? It'd be kinda cool to hook it up with a sound suppressor.

May 26, 2010, 06:04 PM
I made mine into an SBR. Best thing I could have done with it. I have other Ar15 SBR's but my Sig is the one I use the most.. One think I did notice is its not much quieter with my suppressor on.

May 26, 2010, 06:08 PM
Why do that when you can just buy the real thing

WildinstockAlaska ™

May 26, 2010, 06:14 PM
Do what buy the pistol and SBR it, instead of buying a factory Sig SBR?

May 26, 2010, 07:05 PM
We were doing the pistols, but hell, since they let us, we stocked up on the factory SBRs

WildwirelessrouterAlaska ™

May 26, 2010, 09:56 PM
Ok, so what where you selling the pistols for $$? And what where you selling the factory SBR's for$$?

May 31, 2010, 07:16 PM
SO?????? $$$$$

June 4, 2010, 07:21 PM
Hey Wackendog...I like what you did with the 556. Just outta curiosity, how does the whole process work (as far as time, money, and paperwork) to SBR the 556? I noticed you said that the suppressor really didn't have much of an impact...do you think it'd be a waste to even bother with it, or can you maybe recommend a different suppressor? Oh yeah, what was the overall length with the stock, suppressor, etc.? Thanks for the post...take er easy.

September 3, 2010, 01:45 PM
Hey, guys. I am fairly new to the firearms scene. I've been shooting my whole life (mostly pistols until recently) but have just started building my own personal collection. My next purchase will be my first rifle. Instead of going with an AK or AR, I fell in love with the 556 and decided to essentially kill two birds with one stone. I am planning on purchasing a 556 pistol and just adding a butt stock to it (side folding collapsible) (because I would much rather go with the short barrel than the 16" factory barrel). That will basically give me a 556 rifle with a 10" barrel, correct? From what I've currently gathered while researching this topic, converting a pistol to a rifle like this is totally legal in the state of Pennsylvania. Am I correct? I'd really appreciate any help on this (it's quite an expensive purchase after all). Thanks guys!