Military Lake City 7.62 brass is thicker in the base than commercial .308 cases and this Lake City 7.62 brass has 1 to 2 grains "LESS" case capacity.
Lake City 5.56 cases are "NOT" thicker like 7.62 cases because it would cut down too much on its case capacity so they made 5.56 cases harder in the base.
Below you will see the Lake City 5.56 cases have the most case capacity, and the majority of 5.56 and .223 cases are close in capacity.
You can also see that Lake City cases are more uniform than Remington and Winchester cases. And far cheaper than Lapua and why I buy bulk once fired Lake City 5.56 and 7.62 cases.
How Hard is Your Brass? 5.56 and .223 Rem Base Hardness Tests
http://bulletin.accurateshooter.com/2014/05/how-hard-is-your-brass-5-56-and-223-rem-base-hardness-tests/
Bottom line, military Lake City 7.62 cases are thicker in the base to better withstand being fired in larger diameter machine gun chambers. And why machine gun brass is harder to resize.
NOTE, I have the 1992 Hodgdon's manual (book) and it list loads for Winchester .308 cases and also using 7.62 military cases and the max loads are 2 grains less than the .308 cases. And if you Google the subject you will find postings where they checked capacity and the military cases vary between 1 and 2 grains less case capacity. So just work up your loads checking for excessive pressure signs.
Cartridge Case Capacities (shows 2 grains less capacity with military .7.62 cases)
http://kwk.us/cases.html
Old School .308 Winchester Match Loads
http://www.provenreloads-handloads.com/articles/2016/9/18/old-school-308-winchester-match-loads