In Remington 700's, there's only about a 3-4oz spread for the two lengths. In others, like Ruger, CZ, and Winchester, it's a half pound difference between short and long action, savages fall between there - and again, these actions start out a pound heavier than Remingtons already.

So action choice can make a difference - you can add a half to 3/4 pound simply by switching a Rem 700 short action for a Ruger or Winchester long action.

Barrel length, while not a lot of weight, tends to affect balance quite a bit. I never noticed how much difference it makes until I started playing with different brakes on the same rifle. Since the weight is out on a long lever arm, the balance can totally change with just a few ounces.