Ivankonev,
Not as much as you might assume. To begin, I'll say it's a perfectly logical assumption, and it makes perfect sense. Unfortunately, there's a lot of stuff in handloading that turns out to be counterintuitive. What you're really dealing with here is expansion ratio, not just barrel length. Expansion ratio is the volume of the bore and combustion chamber versus that of the combustion chamber alone. While the barrel length will alter the expansion ratio somewhat, case size (capacity) is really the larger factor. In other words, powders that work well in 308cartridges will work well with most barrel lengths, and powders that work well with the big 30 cal magnums, will work best with them in most barrel lengths. Trying to use Retumbo or H1000 in a 308 (or 7.62x54R) just because it has a longer barrel is just going to lead to poor performance. By the same token, using Varget or 4895 in a big magnum because it has a short barrel is also a going to be a problem. Stick with the listed powders for this cartridge, but you may see some improved performance (slightly improved) from the powder in that list that lean towards the faster burning end of the scale.
Like I said, a bit counterintuitive, but if you get the expansion ratio concept, it all makes sense.
