I carry a small flask with an end that is made to drop a specific charge. The ends are removable and can be bought in different sizes. That way there is no measuring to do, just hold the flask upside down, push the lever and the spout fills with the right amount of powder. Now don't just dump it down the barrel, you might get a surprise. Transfer it to a different pouring item before pouring it down the barrel, that way if a spark remains in the barrel, you don't set the entire flask off, when it flames up. I also carry and old piece of antler on a leather thong around my neck, that I drilled to hold 110grs by volumn of Pyrodex. That is the measure I carry and use when I am using my TC Hawken with round ball.
I often make powder measures for friends by using antler, or bone. I take a piece of antler then drill a small hole on the small end for a leather thong. Then on the large end I drill a larger hole that will accommodate the proper amount of powder by volumn. I use one of those brass powder measures to make sure I have the right amount of powder. Many if my friends wear their measures as a necklace all the time. The antler one look nice just as they are. One guy took his bone measure and got another friend to scrimshaw if for him, now he wears it all the time also.