Some infor for you

Yeah, bored.
There are 2 different charging handles, one swiss and the other sig usa. The swiss ones (or modeled after them) are made differently. You can see here. And the swiss ones sit higher, the USA one lower.
The USA one has "UP" on it. Don't know if all of those do tho.



how they sit in the bolt carrier:



Here is the swiss gas blocks compared to the USA one. The two on the left are both swiss.
The Swiss ones can be grey, but also, brown and aged brown. The USA ones will be black.



Swiss pistol grips won't have any manufacturer on it and will have a slide off cap on bottom:



Here is a comparo between the first gen sig usa 556 operating rods and the swiss one on bottom.
Note the spring and winding. Also note the swiss one has a groove in it and the others don't but have a mark on it where the groove would be. Don't know what/why the groove.

 

Nice

 

Thanks so much for sharing the detailed photos comparing the Swiss and US parts,

 

Just a quick note; you have the gas blocks photo called out as "trunnions."

Also, Swiss gas blocks will have a roll mark. Mine are all a dark grey-blue.

 

Thanks for the appreciation. There's a lacking of information out there in the 556 community. I've seen complete BS posted on a sig board (not this) where people that owned one were telling other people the wrong things. I would have chimed in but that board requires a real email account and that's something I don't have as I've used hotmail for years and don't plan on changing.

Yeah, I did type that. Yesterday was last day of pain meds, so a mixed blessing.
Did someone say trunion?


and swiss art work:


You can usually tell if the fire control group is swiss or not because they'll have a reddish tint to them. People sometimes think I'm on drugs when I tell them that...really...but they do. This is one of the first things I look for...the reinforcement bars, then if they are what I'm looking for, the trigger color.

 

The top two charging handles are swiss. You can see their shape here, then look on page 10 of the sig 500_551 armorer's manual to see the profile of those is the same profile in a picture there.
So....does your Sig 556's charging handle have the "UP" on it? I assume that's a Sig USA part.
Looking at the marks on the swiss ones, you can see where they were machined vs. the Sig USA one.

The early sig operating rods do have that bubble in the middle of them as someone posted earlier. My guess is it's a point of stress in the rod so that was added.

Another note is how the spring wire windings are 2 more in the US one v. the swiss one. Mebbe they decided to put more gas through the USA one?

 

Fire control group will also have a roll mark...


Swiss parts (pre transition) can include (up to) upper receiver stamping (finished stateside) trunnion (proof mark), barrel-- no proof, but both barrel and trunnion are Swiss, with final machining done stateside (what I do not know is if the threads were cut to match Swiss pattern, or US?). Fire control group (proof mark), gas block (proof mark), piston, bolt (numbered/hard chromed) carrier (numbered).

 

I have both US and Swiss bolt carriers so I'll take some comparison photos later and post them in this thread as well.

 

I don't have any US BCG's but here is a quick snapshot of a Swiss.

 

I have heard mention of Swiss trunnions in US guns before, and always thought it extremely odd that Sig USA would have removed the scope mount “crest”. Or perhaps the raw trunnion doesn’t have it at all, and it is not an out-of-the-way process to make it without it.

 

Agreed. Same with remixing the barrel profile, but... I've seen companies entirely scrub roll marks in order to claim "made in the USA."
I suppose SiG USA could still claim "US made part" if the finish work was all done stateside. Which, could have included machining-off the crest.
Or, perhaps there was an agreement to run a special limited batch with no proof marks before shipping? Difficult to say...

What I can say for sure-- many Swiss parts do not even match, as they will vary in construction/fabrication based on different production runs.

 

The ones I've seen have a german proof mark "N" IIRC (I'll have to go and look but am sort of laid up at the moment). It's located underneath the barrel by the chamber end.
But like you said we don't know if it was a blank barrelled but not threaded.

Can someone who has a latter version check to see if there's a proof mark? It's by the squared off part that you put the tool on.

Once again, it seems as if the color is an indicator, with the hammers you have shown.
Also, the selectors are grey or black, swiss or US.

 

On the subject of trunnions, is the presence or absence of the hole in the bottom indicative of origin?

 

OK......lower is a pic of the "N" proof mark. From the link, the info on it. So barrels that have this had to have their rifling/chambers done in order to have it be proof tested. So it was done in germany. But as the country part of that proof was omitted....

" The Eagle-N mark signifies that the firearm was proofed in Germany (or West Germany, depending on when the firearm was proofed), while the “N” indicates that the firearm was proofed using a Nitro Beschuss load. “Beschuss” translates as “bombardment,” “shelling,” or “firing” depending on context, and “nitro” is short for “nitrocellulose,” a highly flammable compound used to creates pressures inside the firearm higher than standard gun powder."
...
Provided everything looks good, the pistol is re-assembled and receives the country’s CIP proof mark indicating what type of test it passed (the Eagle-N or “definitive” mark in the case of a German gun), the mark of the proof house, and marks indicating the date of the tests. The firearms is then returned to the manufacturer who can legally sell the firearm domestically or export it to another CIP country.

The “nitro” proof mark is also referred to as the “definitive” (or final) mark of the proof house, as opposed to a “provisional” mark which would generally only apply to shotgun barrels in an early stage of manufacture, which are tested at proof houses to prevent the manufacturer from continuing work on defective tubes."

As there's no country mark, but a Nitro mark.
SIG Sauer Proof Marks and Date Codes - Real Gun Reviews

 

Here's the trunion, with an "0" on the bottom.
Are there ones w/o holes?

I can find nothing in the proof marks for a 0 other than germans used these for dates....but 0 alone isn't a date.

 

same proof marks on the trigger as what LKY13 showed.
Cannot find any info on that one. b2 could have been a date code but they didn't use lower case.

 

Aside from a serial number on the swiss one, they are a different color. IIRC swiss is black and US is greyish. Going off memory on that one tho so a pic would be helpful

 

Is it me or is the swiss spring larger?
IF you have both, have you shot both? How do the triggers compare?
I've not gotten rid of my 556s because of just how sweet the triggers are...and smooth it shoots. Also the reason why they aren't safe queens, but are shooters.

It looks like the only swiss (german) items that have complete manufacturing/proof markings are the gas blocks and triggers, so they were ready to go out and be put into the swiss rifles. The rest were not fully marked, thus my bet is they were destined for export to the US from the beginning.

 

Bosley-- I have owned/shot many of both US and Swiss triggers. Only one I do not have experience with its Mr Shooting Sight's match grade trigger, but I hear great things. I do prefer Swiss triggers, but have shot a few US triggers that were almost (very close) as good as a Swiss. With US triggers it seems comes down to 1. how in-spec the fire control group components are/how in-spec the lower is. 2. has the plunger been properly adjusted... On the range I tend to not notice a difference in triggers when running and gunning as much. On the bench, it's one of my properly tuned Swiss or nothing.

More photos for reference... I do not have a US SiG 556 on-hand at the moment, but I do have a friends 556R I'm doing some work on...

 

I read where someone said the swiss bolts were chromed. That's not true--they are machined. With powdered metal/MIM, the part can be made close enough to the final tolerances where no further machining is needed (if they are OK with the tolerances). When a part is made out of a chunk of metal, it's machined from the rough all the way to the final finish. As the stem of the bolt slides up and down and twists in the bolt carrier, a smoother final finish was desired, thus the stem of the swiss bolt was machined to a fine finish. The US made part was just injection molded and done. If you look on the USA made charging handle, you can see the line of that PM/MIM part that separated the top and bottom of the mold. Look at the swiss one and you'll see the machining marks where it was planed to a flat finished surface. And it stopped there as no more finishing was needed for that part. This is part of the "value engineering" that takes sometimes place.

You can see something comparable to this in an AR bolt/bolt carrier, but in reverse. There's a raised part on the bolt carrier stem that takes the contact as it moves up/down/twists while inside the bolt carrier where it moves is machined to a fine finish. There is no powered metal/MIM parts here in the AR. Sig USA did this to cut down on production costs. IMO the finely machined part is superior. A good analogy is to take a piece of rough sawn wood and drag your hand across it. Then, sand it down in phases from rough all the way to 220 grit as the final finish. It'll be very smooth. The bolt stem is a major friction part, so IMO it should be very smooth, allowing the grease to be the barrier film between both parts, thus taking the 'wear' rather than the metal part itself.