556 Stock Options... not the Wall Street kind.. and a gas system question

So I have finally decided to pick up a 556 Rifle, (and pistol) and ready to pull the trigger any day now but one thing still has me confused. I see pictures here of rifles that appear to be lacking the folding stock contraption on the rear of the receiver yet I don't see any in that configuation on the Sig Sauer website.. Can it be easily removed and a standard AR style buffer tube be installed in its place? I have a UBR sitting in the safe that I thing would go nicely with a 556 Classic.. and one more question.. Are there any advantages / disadvantages to the long gas system over the short one? Thanks in advance, -Joshua.

The Classic has a folding stock of questionable quality. It looks kind of like the original Swiss stock, but its isn't up to the same standards. I removed mine and replaced with an M4 style stock attached to a SAN Swiss adapter that I found used for a good price. Here is a pic of it installed:





Double Diamond LE Supply offers there own adapter that replaces the Classic stock and allows the use of regular AR stocks. It still folds, and obviously doesn't require a buffer or buffer spring. Here is a link to the DDLE adapter:

DDLE SIG 556 Stock Adapter


I ordered one of these, but it was out of stock and I found the SAN Swiss one and purchased it whie it was on backorder. I have since gotten the DDLES version, which I have no use for. Its new, if you want it, I'll cut you a deal on it over buying one from DDLE.

I've been doing some more digging on the net and it appears what I'm looking for is the 556 ER model.. I have yet to find anywhere that it is availible or even listed other than doing a google search and it showing on the Sig website. I have been considering the adapter but I would like to rid the gun of the folding mechanism completely if possible.

I put an AGP folder on my 556. I like it and it locks up tight. I can also just screw in any common buffer tube. Very nice rifle.

Mine is an ER model by the product code, but it had the classic folding stock and hooded front sight. It did, however, have the fish gill handguards. I must have gotten some kind of transitional model. IIRC the original 556 rifles had AR type stocks and no provision for folding. I don't think there are any like that now, except perhaps for ban states.

The ER model without the folder is the SIG556006.
The SIG556007 is the same, but includes the cheap holo sight at a higher cost of course.

You can still use you UBR & have a folder. I recommend the DDLES AR adapter (double diamond law enforcement supply.)

There is another maker for an AR adapter but the DD one I feel is far superior. Do a search, there are pics posted of a UBR stock mounted on an AR folder adapter (it does not quite line up right, its just a pignose mount, its not the double diamond.)

I have a PRS mounted on mine (standard. long gas, classic 556, ddles ar adaptor, prs stock, troy rail- all together weighs a ton), although I do not use any of the adjustability of the stock for the most part, I love the solid feel of the stock.

The long gas system is a disadvantage, it feels like a club. I would choose the short gas system, because of weight issues.

Thanks benzig, I think this was what I was looking for.. also thanks to everyone else for all the other helpful information.

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