I don't use a dipper. Instead I use basically the same measure as shown by Hawg and make sure it's a bit over the top so when I push the gate over, I have a consistant measure. I don't tap or bounce or anything like that as the level will go down and how would you come up with a calibrated bounce? I do tap the barrel after loading or bounce the buttstock on top of my foot a couple of times. If you have to use a dipper, take a healthy dip and scrape the top with a straight edge. A note on putting measured powder into a plastic container, be careful of any static charges that might be present. You can get into trouble more with Black Powder than the other propellants when a static charge is present. Again, consistancy is the key. Unlike smokeless powder, M/L propellants are very forgiving if you are off a few grains either way.
Be Safe !!!
I said a few !!!