Waste is subjective, take a 150 weight bullet in 308, 7mm, .277 or 6.5 and stuff it in a wsm brass. Each step down, depending on the step gradient probably loses 50 to 100fps.
Some could call that a loss, as you loose fps. However look at the b.c. of those bullets. Not a loss if your bucking wind at distance.
A 150 30 cal bullets a ballistic turd compared to a 6.5 150 grain bullet. If I'm in heavy brush likely to pummel a peninsula moose at bow range I'd take the faster 150 from the 300.. but put me in montana on the wide open wind and im going to grab the 6.5 wsm and a long skinny bullet.