Fabrique Nationale aka FN Herstal. The original manufacturing plant is located in Herstal, Belgium. Same company that manufactured the FN FAL 7.62x51 used by numerous european countries as well as NATO countries. Also you may have heard of the Browning HiPower 9mm pistol. Originally
manufactured by FN and continued manufacture under Nazi control when Belgium was invaded and occupied during WWII. Also can't leave out the FN SCAR
I've shot thousands of rounds of 76-77 FN without fail in M14 type rifles as well as FN FAL's and AR10's. Most likely berdan primed, primer and projectile were sealed.
FN Herstal is also the original designer of the military 5.56x45mm SS109 cartridge aka M855 although the US specs differ somewhat from the SS109.
My personal experience with FN or FNB marked 7.62x51 ball has been excellent. I would not hesitate to purchase more. I have not shot any of their 5.56mm but wouldn't hesitate to try it.