Howdy Pards
I just posted this on a different forum, and thought it might be useful here too.
I took a few photos that may make the process of figuring out the correct amount of powder for any particular bullet a bit simpler. This is the method I use, others may use a different method.
The simplest way I have found to do this is to make a little wooden ruler. I made this one from a wooden Q-Tip. This first photo shows a 250 grain PRS Big Lube bullet with the little makeshift ruler. The pencil mark on the ruler marks off the distance from the base of the bullet to the crimp groove. This equals the distance the bottom of the bullet will sit from the case mouth when the bullet is seated and crimped in place.

Here is an alternative method using a caliper. Sorry, the caliper is a little bit out of alignment, I was trying to juggle it with one hand and the camera in the other hand. But you get the idea.

After locking the calipers at the setting in the previous photo, I used them to scribe a mark on the side of the case.
The bullet has been positioned next to the case with the crimp groove even with the case mouth. Notice how the mark on the case lines up with the base of the bullet.

OK, here is the important photo. The little ruler is being held with the pencil mark even with the case mouth. The charge of powder in the case is covering the bottom of the ruler by about 1/16". No, those are not my manicured nails, I asked Mrs Johnson for some assistance in this photo. I took the photo from this angle so the top of the powder charge is visible. The angle makes the alignment a little bit unclear. When you have these things in your hands you can peer at it from any angle to see what you want. This amount of powder is the appropriate amount for this particular bullet, the powder will be compressed by about 1/16" when the bullet is seated and crimped. If one used the caliper method to measure the distance from the bullet base to the crimp groove, the depth extension at the bottom of the caliper can be used instead of the little ruler. But it is probably easier to peer into the case with the little ruler. Once this amount of powder has been determined, any method the shooter prefers can be used to reproduce it. The charge can be weighed, and an appropriate dipper can be used to reproduce that weight of powder. A powder measure can also be set to dispense the same amount of powder.

Here is a photo of everything lined up, from right to left. This particular powder charge is 2.2CC of FFg Goex. The charge in the Lee dipper has been leveled off with a piece of index card. The same charge is in the empty case, the bullet is next to it, and a loaded round is all the way over on the left.

I loaded my Black Powder rounds for several years this way. Now I have a Lyman Black Powder measure mounted on one of my progressive presses. The Lyman measure is set to portion out the same amount of powder as the Lee 2.2CC dipper.
However, if I use a bullet of a significantly different shape, I will recalculate the amount of powder needed.
Hope this is of some use.