SIG 552 and 553 operating systems - a photo detail

[JoshNC]

Thanks Josh. I think I remember seeing stocks like that on COGS website but I just wanted to make sure their different then what I already have.

I like the looks of the non collapsing Swiss a lil more but I'm not sure what the pull is like. What setting would the pull resemble on a 556 stock? I like the middle the best but the lOngest isn't bad either.

Settings are the same on the 556 stock and the Swiss folding/collapsing. Longest setting is same LOP as standard non-collapsing Swiss stock. I run mine all the way collapsed. The photo of my 556-turned-552-turned-553 has a Swiss folding/collapsing stock.

[Dirtyboy333]

Settings are the same on the 556 stock and the Swiss folding/collapsing. Longest setting is same LOP as standard non-collapsing Swiss stock. I run mine all the way collapsed. The photo of my 556-turned-552-turned-553 has a Swiss folding/collapsing stock.

Oh yeah I remember seeing that. I thought it was a 556 stock when I first saw it because I didn't know Swiss made then. Very nice!!!

[The Dumb Gun Collector]

This post is one of those things that keeps me on M4 Carbine.

[Dirtyboy333]

Man, the more i learn and research the 55x the more valuable this thread gets.

Josh, is the 553 BCG in the pics U.S. made? Also, is the little "curved" rail on the 552 BCG indicate that it's a FA carrier unlike the straight 553 carrier?

[JoshNC]

Man, the more i learn and research the 55x the more valuable this thread gets.

Josh, is the 553 BCG in the pics U.S. made? Also, is the little "curved" rail on the 552 BCG indicate that it's a FA carrier unlike the straight 553 carrier?

It is an early 556 bolt carrier (semiauto); these early 556 bolt groups were Swiss made. As far as I know, all 552 carriers are fullauto.....then again I have yet to check the bolt carrier in my factory semi 552. I will check it out and report later.

[Dirtyboy333]

Ok thanks alot Josh

[Dirtyboy333]

Josh: Is there a way to tell if a 556 is using a Swiss bolt??? I ask because my uncles early ER definitely has the swiss gas block with the proof marks and different finish but i told him a while ago that his BCG was US made. The reason i thought that is because there was no serial number or any marks whatsoever but it turns out that may not be an indicator.

The bolt itself is black like my US bolt (slightly different shade) and its finished all the way down to the end (firing pin) instead of just the "head" being finished like ive seen on serialized Swiss bolts. Also, the carrier is black in color almost like its been nitrided. My carrier is silver.

Again, its not really a big issue. I would just like to be able to identify it correctly and am wondering if there are any tell-tale signs of its origin. (oh, it is better machined than mine but nothing thats strikingly different to my novice eye. Theres a 90 degree corner on my bolt head that has a little bit of overflow(?) that i can catch my fingernail on. His has none of that and is smooth)