[aa1911]

I always do it by volume whether prepping speed tubes at the house or out in the field. Can't say I've ever weighed black powder.

I just use a brass measure that has a swivel funnel on top so if there's a bit of excess, it gets wiped off. But I tap mine just a bit, like you said, as long as you do the same thing every time, you will be fine.

it's not really that exact of a science with black powder, a grain isn't going to make enough difference.

Same with tamping the projectile/powder charge, try to tamp with the same amount of taps and pressure each time.