Does a SIG 556 have a treated barrel?

[ABNAK]

I notice one "Gen" has dimples popping outward and one has dimples going inward (above the mag well under the ejection port).

[Bret]

You're looking at two different parts of the rifles. They're the same on both. The ones that look like they're popping out are towards the rear of the ejection port. The ones that look like they're going inward are weld marks under the ejection port.

[ABNAK]

Okay, got a chance to look closer at it today. It has the mag release that sits more forward, looks like the oval AR type. Serial number is 015XXX (don't recall if there's another digit or not but the first 3 are 015).

I looked closely at the exterior of the barrel and it doesn't have that "sheen" that nitrided parts do. Now I know nitriding/Meloniting can look a little different depending on who does it, but I've seen enough to recognize that shiny and slick-looking black color. This barrel has more of a dark gray, almost park color to it. In fact it matches the rest of the gun's finish quite well.

I don't need the gun, but since I have AR's out the wazoo my buddy might consider a trade for one of them (although he has quite a few too) and it'd mainly be for the novelty of it. If the barrel is nitrided or not will make the difference to me whether I even make him an offer. If it's untreated I have zero interest in it.

[JoshNC]

Okay, got a chance to look closer at it today. It has the mag release that sits more forward, looks like the oval AR type. Serial number is 015XXX (don't recall if there's another digit or not but the first 3 are 015).

I looked closely at the exterior of the barrel and it doesn't have that "sheen" that nitrided parts do. Now I know nitriding/Meloniting can look a little different depending on who does it, but I've seen enough to recognize that shiny and slick-looking black color. This barrel has more of a dark gray, almost park color to it. In fact it matches the rest of the gun's finish quite well.

I don't need the gun, but since I have AR's out the wazoo my buddy might consider a trade for one of them (although he has quite a few too) and it'd mainly be for the novelty of it. If the barrel is nitrided or not will make the difference to me whether I even make him an offer. If it's untreated I have zero interest in it.

Who knows man. It’s a crap shoot. Exeter could potentially give you your answer. Maybe. I frankly on’t trust that they have anyone there who would know.

[JoshNC]

Okay, got a chance to look closer at it today. It has the mag release that sits more forward, looks like the oval AR type. Serial number is 015XXX (don't recall if there's another digit or not but the first 3 are 015).

I looked closely at the exterior of the barrel and it doesn't have that "sheen" that nitrided parts do. Now I know nitriding/Meloniting can look a little different depending on who does it, but I've seen enough to recognize that shiny and slick-looking black color. This barrel has more of a dark gray, almost park color to it. In fact it matches the rest of the gun's finish quite well.

I don't need the gun, but since I have AR's out the wazoo my buddy might consider a trade for one of them (although he has quite a few too) and it'd mainly be for the novelty of it. If the barrel is nitrided or not will make the difference to me whether I even make him an offer. If it's untreated I have zero interest in it.

Who knows man. It’s a crap shoot. Exeter could potentially give you your answer. Maybe. I frankly don’t trust that they have anyone there who would know.

[ramairthree]

Below are some closer up pictures to illustrate the difference between the two Sig USA lowers. I'd called them second and third generation lowers. ramairthree has what I'd call a 1st generation lower pictured above. There's a chance that there are other variations, but I'm not aware of them if there are. The first picture is me gripping the Sig556 Classic rifle lower. The second and third pictures are of me gripping the Sig556 Classic SBR lower. I ordered this SBR from Sig and had to wait over a year for it to be delivered to my dealer. It was delivered right before they stopped production. I'm speculating, but it's likely that there are rifles that also have this lower and it's likely that there are SBR's that have the 2nd generation lower.



As you can see, the magazine release of the 3rd generation lower can be pressed without shifting the grip, but the magazine release of the 2nd generation lower can't be reached without shifting the grip.

Yes, I had to get an aftermarket grip that let me selector lever and mag release without a shift in grip. When I grabbed a used 556R at a good price, the company no longer makes the grips.