What are the differences b/t the "new" designed SIG 516 bolt carrier vs. the old LWRC knock-off that came with the first production run rifles?

Any performance differences? Issues?

Does anyone have a pic of the new bolt design?

Out of curiosity...will a LWRC bolt carrier group work in the SIG 516? I would think it would since the original SIG 516 bolt carrier group design was an exact copy of the LWRC design.

All are very interesting questions. The new bolt I believe does not have the OTB flutes at the end or somethings. The rest I have no clue about. I would assume that it would work. Where are you located? Find someone in your area that is willing to do a swap. If the piston rod still terminates in the same place as it did before the change then I can see no issue with swapping them out. In fact that would be a nice upgrade for Sig owners if they aren't happy with the new bolt.

There's a forum member (Darith) on here that posted pics of the new BCG.  If you do a search, it should come up.  Or he'll be in here shortly to answer your questions.

So, are all SIG 516's that you find new at gun dealers shipping with the new bolt design? I'm wondering if dealers had to send their's back to SIG to get the bolt milled due to the "hush" recall.

I don't know.  People were saying if you send your rifle back to SIG for repairs, they'll switch out the BCG for the "new" one.  This wasn't the case when I sent mine back (weird mag catch issue).  I got the original BCG back.

Maybe I was getting two sites confused... here is the thread talking about the difference in BCGs.  LINK

That link was a good read, I wonder what exactly in the claim from the LWRC patent they infringed on because all these carriers have about the same stuff.  The HK is ahead with keeping the guide rails.  Take a look at what a hack job these carriers are, if you're not aware of the steps to make one

1-you turn it on the lathe and you have to leave a huge ring around where the piston lug is, so you have like a 2 inch ring about 3/8 inch long.(2 lathe operations unless dual spindle handoff)
2-then you have some 4 axis where you put in the cam groove and all the other stuff, this is when you have to wack that gigantic ring that is attached.  It is impossible to machine blend 2 surfaces, 1 will always be higher and since the turning of the od put the id hole that locates the bolt you have to have that as your master surface, so you have to slightly undercut the area where the ring is so it doesn't disturb the contact surface the carrier will ride on.  In the end it looks like you get about half the line contact.  It's already line contact so it is small in area but when you cut it away it is like you get 2 point contacts instead.  It doesn't relate to much except a wear issue but the carriers tend to look like hack jobs.  

*I don't give a crap about machine marks, I like them, but it does show the setup wasn't dialed yet, or the operator had a bad day.  

What are they thinking in lightening the carrier, I mean really, take a look at the trends, We had a Carbine buffer, then a Heavy, then H2, H3...H6.  With altering a total system you can do anything but if this is to be considered an AR like the rest there are a few parameters you should keep.  

Conservation of momentum, if you have a heavy mass in motion, like the bolt group, then it will more easily overcome the challenges of stripping the round rom the mag and chambering (If you go too heavy its like a limp... and doesn't do anything).  That is the only area a gun should be heavy, I think it is more important than having the barrel heavy and all I do is hose out bursts well over 100 rds at a time.