Looks like Israel decided to pass on the expensive 6.8x51mm round and stick with the old-fashioned 7.62x51mm cartridge.
"The Israel Defense Forces (IDF) have reportedly acquired a version of the 6.8x51mm M250 light machine gun that Sig Sauer developed for the U.S. Army, but chambered to fire the NATO-standard 7.62x51mm round. Sig Sauer’s design may now be in line to supplant at least a portion of Israeli Negev light machine guns 5.56x45mm and 7.62x51mm, variations of which are current in IDF service."
https://www.yahoo.com/news/israel-buys-7-62x51mm-version-202443582.html
"The Israel Defense Forces (IDF) have reportedly acquired a version of the 6.8x51mm M250 light machine gun that Sig Sauer developed for the U.S. Army, but chambered to fire the NATO-standard 7.62x51mm round. Sig Sauer’s design may now be in line to supplant at least a portion of Israeli Negev light machine guns 5.56x45mm and 7.62x51mm, variations of which are current in IDF service."
https://www.yahoo.com/news/israel-buys-7-62x51mm-version-202443582.html