Anyone know if the charging handle that comes with the 516 is of a different spec that a standard M4 type rifle? I just tried installing a Rainier Arms/AXTS Raptor and it was a no-go. It started out fine going into the upper but about 60% of the way in, it felt as if everything was too tight. At 80% inserted, I knew it was not going to work. The bolt carrier fit in the Raptor channel just fine and if you just install the Raptor without the BCG, it slides in and makes it's way past the piston rod with no clearance issues.

If anyone knows of an ambi CH that will work, please post up.

Here are some pics of the charging handle that came with the 516 along with the Raptor. Notice that the top flat sections are different sizes.





Raptor on the left:



Sig M400 upper (square forge marking)



Sig 516 upper (keyhole forge marking)

Should be the same for the 516, I have had BCM gunfighter on mine for about two years now, no issues.  This is the first I've heard of a charging handle not working on a 516.  

BigRat

I'm running a BCM Gunfighter in mine with no issues.

I'm running a BCM Gunfighter as well. No issues.

My 516 works fine with the Raptor charging handle. It was a little tight at first, but after some action and lubing contact points it's smooth. Try lubing any points of contact.

Thanks for the feedback. Will try lubing it.

As an aside, how tight was it? With mine, you would basically have to hammer it in with your palm.

I looked into it a bit further and it appears as though the bolt carrier piston rod cup interface is the problem area. Of those who posted stating the the BCM GF gives you no problems, what generation bolt carrier are you running (1,2, or 3)?

V1 was the one they got sued over
V2 is the one they ran on gen 1 516s
V3 is the new one with the extra "bridge" on the lower rear of the bolt carrier

For reference, I am running V2.

(Pics borrowed from Darith):

There really isn't a "V3."  That's just the full-auto version of the new carrier.



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Thanks for the clarification. So what version are you running if you don't mind me asking?

Just did a function check with the Rainier Arms Raptor charging handle in my 1st Generation 516 with the 'v2' carrier:

Fitment and the charging action works fine 100%.

I also dabbed grease in 4 places of contact to reduce friction against the receiver. I used this grease:

Pro Gold Lube Grease

Scroll down to the 'charging handle' section:
Lubrication

Hope this helps...

Thanks, I'll give it a try. Its funny the, Raptor I have fits in all of my other guns.

I am running the latest version of the BCM in my Gen2 SIG. I had an older version in my Gen1 SIG. I've had no fitment issues with either generation in either rifle.

I'd guess you've run into a bit of tolerance stack. An upper that's a bit tight combined with a handle that's a bit big.





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Any update on the fitment? I'll try to post a video of the Raptor fitting and functioning with my 516 when I get a chance.

I works now. I had to cycle it about 1000 times, while taking it off and cleaning out the aluminum shavings every so often. I think it was a tolerance spec issue with the keyhole upper as that same CH worked like a dream in my m400 which has a square forge marking.

The more I learn about the AR platform, the more I realize that "acceptable"  mil-spec tolerances are far and wide ranging and that precision components sometimes have issues as a result.

Good to know you got this working. They put a note on the bottom that it may not fit on some 516's after you made your posts ("*** May not fit on some SIG AR’s, specifically the 516 Model") Raptor.

Would you mind taking a photo of the shaved off area? Rainier Arms may need this for their reference.

I took a bunch of pics but my camera could not decide where it wanted to focus. This shot tells the story best:

(Top is the 516 Raptor, Bottom is M400 Raptor)


That's not a reflection on the little lug hanging off of the forward portion of the top charging handle. A lot of material wore off before everything was up and running smoothly again. Luckily, this is not a stressed area as it is only used to key the CH into the top portion of the upper.