There is one peckerhead on YouTube that has a bunch of vids trash talking the 516 and the 716, I forget what his beef was with Sig but he was truly engineering failures in the rifles.
I had a 716 that was nothing but reliable and accurate. Great rifle. Buddy of mine has a 516, same. Never...
The gentleman at the Lithonia store was extremely helpful for me as well. Opened up the case and then under the register. I bought the 9mm Federal 200round bulk packs for $17 and the 100 round packs for $9. I was completely out of 9mm, so I ended up buying over 2,000 rounds yesterday there.
My first little rifle was a Sig M400. Really good little rifle for the money. All I heard from a friend of mine is how it was nice but not quite up to the snuff a 6920 Colt was, b/c it wasn't "mil-spec".
Time went by and I sold it and put the money towards a Sig 716. It was a damn fine gun...