From a engineer stand point you have to be tracable to a engineering weight standard any thing else is a calculated guess pure and simple. And by the way check weights come in incerments so you can zero at almost any charge weight needed. And are on par with or cheaper than a box of bullets.
Yes you need to be, and can beconsistant using penneys, nickles and a few sorted bullets, but why not just do it right? Its taking one more veriable put of the reloading equation. Sometimes your load is faster than the listed velocity not because of a fast barrel but because your load is realy 0.02-0.03grs over and than could be very bad. I find it a good thing to know of much margin of safty I real have not just a guess.

I do not mean to afend anyone but if I want i can actual produce sometings weight and atomical make upin a scanning ectron microscope. many ofus posters do very neet things. And some like myself don't spellorfind mistakes in our post well, Be gentil.