How does the 6.5 creedmoor compare to a 308 as far as recoil with both rifles being the same weight ?
Same weight rifles, same weight bullets, same speed (or very similar), recoil ENERGY is the same (or very similar). That's Newtonian physics.
Now, what you FEEL can be the same, or much different. This depends on other factors, which include stock design, and fit to the shooter.
Now, you can calculate the small differences between things, and then, show on paper, how they are different, and they are different, but can you FEEL the difference?? I can't. I can't tell you from the feel of the recoil if it was a 140gr 6.5mm or a 150gr .30 at similar speed.
BUT, I can tell the difference between the feel of the same ammo in differently stocked rifles of the same weight. You? I don't know, maybe you can, maybe you can't. Everyone is different and FELT RECOIL is entirely subjective. Calculated recoil is a number. Felt recoil is what you feel, and can be different for every different individual.
I can definitely feel the difference shooting the same ammo in a rifle with a straight stock and a rubber buttplate compared to one of he same weight with several inches of drop to the stock and a steel buttplate.
Can you?