The "one powder" idea is a novice concept that never really works.
^^^^ This.
Reloading isn't a simplex linear programming problem. If this criterion is really important, I'd politely steer him towards factory ammo.
Good friend he can’t buy factory ammo either. Maybe he has a idea and learns he needs 1 or 2 more powders than he was thinking. You know after he learns a little bit. Not everyone knows everything when they first start something new. He also has a friend to help him that knows what he’s doing.
Anyway now that all the negative stuff is out of the way. H4350 and H4831sc will both work with his 243 and 300win. I use H4350 in 22-250AI,6 creedmoor, 243’s,friends 6.5 creed and my 260. I say that to say he might can use it for his 300 savage and 308? The last two I just don’t know? I use ‘15 in my wife’s 250AI and varget for others 308’s.
No clue about pistol powder. Good on you for helping him though. As you know now is not the best time to start loading but getting some things as he can and learning the basics is a start.
