Have a question about a Sig Sauer Factory Rifle, inside the barrel extension between the chamber and the locking lugs on the right side there’s a small round piece of steel inside, it’s maybe 1/8 inch round and an 1/8 inch high and would kinda line up where the extractor on the bolt rotates into the extension. The top of the little piece of steel is rounded, it almost looks like a ball bearing maybe.

I didn’t get a picture.

I’ve never seen this that before ?  Why is it there and what does it do ?

It ran fine, all except for when trying to setup type 1 and 2 malfunctions with empty cases and snap caps.

I didn’t google or search here for it, sorry if it’s been asked before, just figured you guys would straighten it out pretty quickly for me.

It’s there to hold the extractor tight up against the rim to aid in extraction.

That was my guess, there was 10 people in the class and none of us had seen that before.

I’m reaching back to 2016 memories here, but I think Sig stole HK’s engineer behind the 416, and they built the 516 to mimic the performance of the HK carbine.  One of the HK design features was a supported extractor, and sig copied that as well.

Take all that worth a grain of salt.

Yeah I don’t know, learn something new everyday, it must be Ok I haven’t read or seen anything about the guns breaking extractors. I imagine if that sort of thing was happening I’d have seen some posting here on the board somewhere.

The Caracal 816 (UAE's version of the HK416) has this:
Attached File


Look about the same in your Sig?

I'm assuming this is only on the 516 Sig's or do you find it in the M400 lineup as well?

Yes it’s extractor support, all of my 516 and m400’s have it.

A little more digging and it looks like the M400's did use it on some guns in 2012 and may have it in all. Here's a screenshot from someone in 2012 of their M400 on another forum:
Attached File


The MCX reportedly has this added as well.

Interesting tidbit of info, thanks for sharing OP.

I'd be curious to know if replacement barrels from Sig come equipped with this feature and if there are any minor revisions to the extractors to help it interface better with the post in the extension. I'd also be curious to see if there's any appreciable wear from the contact with the outside face extractor on the metal tab in the extension or with the extractor itself.

The 716I has it as well. Well now we know why.

As stated...

"extractor support in the barrel extension. We consider this a high-end touch and one that Sig uses in its 516 series rifles. When the bolt of an AR is in battery, the extractor is an unsupported area of the bolt head. In an overpressure event, the hinged extractor acts like a relief port and lets gases blow it open. Sig places a pin in the barrel extension that essentially braces the outside edge of the extractor, preventing it from opening when the bolt is in battery. It’s a great safety feature providing insurance against a receiver blow-out if you suffer an obstructed bore malfunction."

So it’s for 300 BLK!

That’s exactly the same Wangstang. Thank you for providing the picture and Thank you everyone for helping out.

On our next outing, I’ll get pictures of the extractor and all. The rifle has about 1000 rounds down the pipe according to him with no malfunctions of any kind.