Question about .308 and 7mm-08 barrels

[bydhrpr]

What can one expect in the way of bullet velocities when comparing 22 inch and 24 inch barrels in both .308 and 7mm-08? Is it worth going for the longer barrel?

What about Encore barrels? What type of accuracy can one expect from an Encore in each of these calibers? I am also considering a Remington model 700.

I would appreciate your thoughts as I am looking for an accurate "carry gun" that is effective on deer out to 500 yds. I plan on topping my new rifle with a Leupold 4.5 x14 50mm. I would love to hear what anyone else may use, as a compact and light set up for deer sized critters out to this range.