Sig 516 Piston Upper Bolt Carrier [Archive]

View Full Version : Sig 516 Piston Upper Bolt Carrier

Bret

08-04-20, 22:15

kyjd75

08-05-20, 04:36

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?
https://i.postimg.cc/k4K1xcjb/Sig-516-BCG.jpg
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

08-05-20, 05:01

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. https://uploads.tapatalk-cdn.com/20200805/4f81e4c6b50cbc855c042d778da843df.jpg

Sent from my SM-N975U using Tapatalk

kyjd75

08-05-20, 06:48

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

08-05-20, 16:07

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

08-05-20, 19:11

kyjd75

08-06-20, 05:09

Interestingly, here's the sticker that came on the box. Notice it says "Semi".
https://i.postimg.cc/Fsz92ct2/Sig-516-Upper-Box-Sticker.jpg

Here's the 516 upper ready to roll on my M16A1 lower.
https://i.postimg.cc/m2nbRDBh/Sig-516-Upper-on-M16-A1-Lower.jpg

Can't wait to hear a report on how well (or not) it performs. I think the "sticker" is just the normal civilian production sticker that Sig uses for its regular civilian version 516s. As I said earlier, I have two 516s with the FA BCG, and two with the SA BCG. Of course, all are actually SA only lowers. None of them have ever malfunctioned even once. In my experience the 516 is an extremely robust, reliable rifle.

Bret

08-06-20, 08:41

I'll be happy to provide a report. I might even do a low (and I do mean low) budget video. Interestingly, I looked on Sig's website and the 516 is nowhere to be found. What's up with that?

kyjd75

08-06-20, 12:23

I'll be happy to provide a report. I might even do a low (and I do mean low) budget video. Interestingly, I looked on Sig's website and the 516 is nowhere to be found. What's up with that?

From what I understand, Sig has restricted the 516 to military/LE purchases only for the time being. Not sure exactly why, as the 716 is still available to the civilian market. I did talk with a Sig rep a couple of months ago about this and he advised that even though it is no longer listed on the website, if a civilian wants to purchase one, he will still be able to do so.

Bret

08-06-20, 17:54

Thanks for the insight.

omegajb

08-06-20, 18:50

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.

Sent from my SM-N975U using Tapatalk

kyjd75

08-07-20, 09:53

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.

Sent from my SM-N975U using Tapatalk

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.

Bret

08-09-20, 18:08

I put 150rds of IMI 55gr FMJ through the 516 upper using my M16A1 lower. Unfortunately, I left an H2 buffer in the lower instead of installing an H1 buffer like Sig recommends in their instruction manual. As a result, I had two cartridges that didn't feed due to short stroking. That's completely my fault. Otherwise, function was fine with the spent cases going in to a nice small area.

masterdrago

08-09-20, 18:27

Bret, I would really appreciate a favor. I would very much like to know what the port sizes are on your gas valve. It appears that the valve is different on the 16", 14.5" & the 10". I've got the valve for the 10 & 16. 16 has smaller ports. Even better would be a part # for it which unfortunately would most likely require a call to Sig. My wait time the other day was 45 minutes. I used a numbered drill bit set to measure mine. Thanks

https://i.imgur.com/0u8XlTK.jpg

Bret

08-09-20, 22:03

I have a gauge pin set, but it only goes up to 0.060". The smallest hole measures 0.039", the middle hole measures 0.047" and the large hole measures between 0.060" (max from gauge pin set) and 0.063" (my smallest drill bit larger than 0.060"). I sure hope that Sig improved their process for drilling gas port holes. I've purchased multiple gas plugs for my two 556 rifles and their measurements are all over the place.