I got out there today. I fired one full mag (20rds) flawlessly. Handed it to my wife, went back to the 50 BMG and she and my Dad came back and told me it was failing to extract. I took it from them, put in a fresh 20rd mag, fired one shot and it also failed to extract.
This was with factory FNH 40gr ammo.
Gun is brand new, so maybe it's not broken in yet. Maybe it is because I didn't clean and lube it (shot it right out of the box new) before we shot it. I'll try again after a thoroughly clean and lube it.
FWIW, I did take it apart when I got home, took the barrel out and placed each spent case in the barrel. Seemed not all the necks of the cases expanded the same. Some look more expanded at the neck and don't seat all the way in the barrel. The ones that didn't expand like that seat deeper, but those are much much tighter and more difficult to pull out. I'm not a gun smith and don't know if that means anything, but found it odd. I'll snap pictures of the cases later.
This really made my day sour, though. I have a Sig 716 that has been picky as hell with ammo and was scratching and denting brass. So I bought some TulAmmo to try and break it in and that damn ammo jammed up so tight (FTE) I thought I'd never get those rounds out. Had to hamer the bolt shut, take it apart, and pry the bolt open from the under-side. I gave the same rounds to a range buddy and his HK and FN SCAR cycled the TulAmmo 308 150gr flawlessly. It fires Winchester 308 perfect, Winchester white box 7.62x51 flawlessly, but it'll once in a while FTF/FTE Federal Lake City M80 and absolutely won't cycle TulAmmo.
The Sig 716:
Sig 716 denting cases normal? - SIG Talk
Second outing with the Sig 716 - SIG Talk
Sig 716 Failure To Feed/ Failure To Extract - SIG Talk
So now I have two guns bought new having issues.