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Folding hinge onto a 556 Pistol?

227 Views 3 Replies 3 Participants Last post by  LKY13
Found a Sig 556 Pistol I'm considering buying for a SBR build. I found the 556 Stock along with the button, pins, etc. The question is where/how does one fit the original folding hinge to a pistol or is it possible? Right now it appears it has sort of plate secured x2 allen screws.
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Do you have any more pictures? If it's what I'm thinking, that receiver was designed for a buffer tube and stock, but it's hard to tell from that picture.

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Basically after much research. It seems most people chop down a existing 556 Patrol Tactical with the shortened rail. Or Go the pistol route and ad a stock adaptor like a MCX folding mechanism from Sig and call it a day. My original thought was to install a folding mechanism from a 556 Patrol full length onto the pistol, but that seems be cloak and dagger. I called up Sig and they didn't really offer any real advice. The stock adapter that's currently on is being sold with the pistol. No idea as to it's origin or function.

My original thought was making it as close to a 556 factory SBR as possible " 552 commando" with the full length folding stock. I'm having trouble sourcing that hinge that allows for that?

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That end piece is just a pig nose adapter. Remove the two allen bolts and the outer portion will come off. Then there will be an inner threaded portion that will unscrew out of the inner threads. Then you are free to add any M4 type buffer tube or folding adapter you like.

I just sold a Hera arms and Sylvan arms folder cheap, but one of these will work. Alternatively, I've added a KNS 1913 adapter and MCX folding stock a few times. Just be sure to get the KNS with the flange to retain your rear spring and detent for the rear take-down pin.

Lastly, I currently have on a 556xi a KNS 1913 adapter with flange and Zhukov stock with Haga Defense 1913 hinge adapter. If you're looking for something unique, but very comfortable / functional and still side-folding...

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