I ran simulations on Quickload for your cartridges and bullets your using and came up with these common powders. There are more but these gave the best speeds. In order RL26,V560, IMR7828SC, Magpro and RL22. When trying to utilize one powder for both rifles you may have to give up a little accuracy or speed on one or both to accomplish this. I'd give up speed first. That's what they have range finders and ballistic software for. As for starting reloading, the best advice I can give you is get a Hornady or Nosler reloading manual and learn/memorize the safety and reloading sections. That'll get you going and keep you from hurting yourself or others. For a starting OAL on a hunting rifle I use mag length to start, verifying that length is not jamming the lands. Find the powder charge that seems to want to group and the work backwards from the mag length. I've done this for thousands of loads and it is the easiest and simplest way for shooters new to reloading. You certainly can do it with other methods and I do but I've taught many people how to reload and they all still have all their digits and eyeballs! Good luck and let us know how you do.