Sig 516 Piston Upper Bolt Carrier

[Bret]

I purchased a 14.5" Sig 516 piston upper half. I'd like to run it on my M16, but I'm not sure about the carrier. There's one on GunBroker exactly like it that the seller claims is full auto. I'm thinking it looks more like a semi auto, but it pretty different than a regular DI carrier anyway. Is it a full or semi auto carrier?

[kyjd75]

I purchased a 14.5" Sig 516 piston upper half. I'd like to run it on my M16, but I'm not sure about the carrier. There's one on GunBroker exactly like it that the seller claims is full auto. I'm thinking it looks more like a semi auto, but it pretty different than a regular DI carrier anyway. Is it a full or semi auto carrier?

I own four 516s. The bolt carrier in your picture is Sig's version of a full auto bolt carrier. A couple of my uppers were purchased as military overruns, and they came with this style of BCG. For what it is worth, you can also run an LWRC piston version BCG in the 516 as well. But, the answer to your question is, Yes, this is a full auto bolt carrier from Sig.

[omegajb]

I own four 516s. The bolt carrier in your picture is Sig's version of a full auto bolt carrier. A couple of my uppers were purchased as military overruns, and they came with this style of BCG. For what it is worth, you can also run an LWRC piston version BCG in the 516 as well. But, the answer to your question is, Yes, this is a full auto bolt carrier from Sig.

Is the area circled how you tell if it's a full auto bolt carrier?
I bought 2 of those military contract overruns and they were the best deal going.

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[kyjd75]

Yes, that extra extension on the carrier is what makes it a full auto version. A little different from other full auto bolt carriers, but according to those who have full auto 516s (Sig forum) it does work. The semi auto version does not have that extra protrusion (a couple of my 516s have the semi style carrier as well).

[Bret]

Great. I really appreciate y'all letting me know. Since I primarily bought it to run it on my M16, I was going to be very disappointed if it was a semi. An NFA length 14.5" barrel with a semi bolt seems like a waste to me. Actually, I absolutely don't understand why Sig would even make a semi bolt carrier. It will be very interesting to compare the Sig piston upper to my T91 piston upper.

[Bret]

Interestingly, here's the sticker that came on the box. Notice it says "Semi".


Here's the 516 upper ready to roll on my M16A1 lower.

[omegajb]

According to Wikipedia, the 516 was discontinued in 2019, but the source they use is a forum.
So take that with a grain of salt.

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[kyjd75]

According to Wikipedia, the 516 was discontinued in 2019, but the source they use is a forum.
So take that with a grain of salt.

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Yeah, talk is cheap. No doubt that Sig has removed it from their civilian catalog, but pretty sure it is still listed in their military/LE catalog. As well, a Sig rep told me personally that it was still available for military/LE and even civilians as a special order item. Sig has sold thousands of 516s to mil/LE units around the world. Parts and service for these weapons isn't going anywhere soon.