Moose 4 GOD,
think of it as an adventure. You get to play with a few different powders, bullets, primers to see which one your new gun will like. Any loads that were real consistant in your other rifle will be the first to try in this new one but if they don't work then you get to try the ones that didn't work for your other gun. The faster twist means that you can use heavier bullets and the shorter barrel means that you MIGHT not get velocities that are as high. it usually follows that your standard deviation and mean average deviation will grow but 2 inches will probably not make a big difference there.
Keeping things simple is always the best bet but you can get real involved in all the little things too. If that is what you like then you can test charges at .1 grain increments with three different powders, bullets and primers and really burn some time and money looking for a load to meat your neads. I usually settle on a single bullet and primer and then go through testing the three hottest powders. I take the most accurate load of each of them and play with seating depths and when I have the three most accurate loadings with those powders I get out the chronograph and see what it says about standard deviation and mean average deviation, maximum velocity spread of a twenty round sampling of each - that also gives me a good idea of average velocity for each of the loads. Then I shoot each of the loads for a month with different conditions at different ranges in my area to find the most consistant of the three. Then I can do further testing with different primers if there is any reason to and when I have the best of the best and it performs at the velocity I expect or better I can load it up with confidence and shoot it at what ever I choose to use it on.
