If you're going to use this in a .45acp, overall length is 1.260 max. With some of the variations of the .45acp pistols, it's best to seat to 1.250 because in some cases, the Para_ord mags need them shorter and there are some tight/short chambers out there.
For a kid, I use 4.7 of 231. It's also a pleasant practice load for older people.
If you have a star or a press that can accommodate finer powder, titegroup is popular, but not for a Dillon. I shoot this in everything from a Lichtman/Simmerling to a comp auto.