shoot-it-as-fast-as-i-can-pull-the-trigger long gun
If that is your objective the .308 is not a choice. The recoil makes it nearly impossible to do the rapid fire you desire.
The reason the military went to a .223 was because the m-14 (a .308 rifle)was impractical to use in automatic mode. We were thaught to shoot in 3 round bursts. If look at the bullet most .223 ammo is 50 to 65 grain bullets or about 1/3 the weight of your average .308 bullet (150 to 180 grains).
With the Colt you have the option to do both, a little of "spray and pray" and after you got that out of your system, you can start aiming at targets.
Another warning, I've never owned or fired a Vepr, but generally you can forget any real accuracy with any of the eastern block type rifles. And the .308 is intended to be a medium to long range bullet.
Good luck, shooting is nothing like playing guitar.