There are alot of people moving into the 6.5 Creedmoor category, moving out of the .308 game. The 6.5 Creedmoor uses skinnier, lighter bullets and its faster downrange than a .308.
However, the 6.5 Creedmoor is very popular as a great selection for medium to long range (500-1000 yards) shooting. Which is why the military has added this caliber into some of their rifles for long range targets shooting.
Ballistics speaking, the skinny 6.5mm bullets perform exceptionally well, very closely matching the ballistic profile of a 300 Winchester Magnum, but with much less recoil and cost.
It’s possible that the popularity shift to the 6.5 Creedmoor, is the better ballistic cartridge than .308 Cal due to performance consistency. The .308 was designed in 1952 for a semi-automatic military rifle, while the 6.5 Creedmoor was designed in 2007 for better long range target performance in a bolt action rifle. Which now has evolved into the AR platform of weapons