My "guess" would be that, our " American" High Speed loading machines, of Today, DON'T weigh, the Powder very consistently, coupled with, POOR lead quality as noted, above ! The Manufacturers don't care, anymore, as they are, busy, trying to "fill the Bill" for UNDER $20 a Box, Bulk ammo for, the Plinker crowd.
I have a few boxes of 1990- 1991 ( a mere, 30 years, ago ! ) .22 Win. Super X that, are copper plated, 40 gr. that go, 1180 - 1200 FPS (actual, Chrno'd ) and I have shot the BEST groups so far, in my Ruger 10-22, 22" SS with, them. So, I KNOW they "could" build good Chit, IF they wanted to ! Since, I know that, most American stuff, has "Flyers", as stated by 1Merlin and others, I'm going to start using, Lap SK Std Plus @ $5 per 50 and SK Long Range @ $8. IF, I have to for any, serious shooting and at,.. Cottontail Rabbits !