You'll like the nipples. I'm a big fan of Treso Ampco nipples.
if you don't use the same amount of force tapping, and don't tap each and every charge the same exact same amount of times and use the exact same amount of force tapping,..... you'll get charges that are more tightly compacted or less tightly compacted than other charges are.
I think you misunderstand the effect tapping the measure has. It doesn't compress the powder, it settles it. Once the grains have settled and reached equilibrium, whether it's one tap or two, they will not settle more. And the amount of force used to tap the measure has nothing to do with how the grains settle - they settle into place by gravity, not by the shock impact on the side of the tube. And besides, if you're benching the gun, why are you in such a big hurry?