Within the same brands, or across brands (countries)?
Balgarian was the worse having highs in the 1500s and lows in the 500s
Romanian mil surp not far behind 1500-800s
The Chicom stuff was 1100-800
S&P old lots (70s dated) 1650-1100
S&P new lots (90s dated) 1650-1450
I prefer no more than 100 fps vary.
All of my 7.62x39 is way inside of 100fps.
With a little bit of work we can pull down all the S&P, repowder it to AA #9 and get 1650-1700fps all day long.
We are going to pull down the commie milsurp, keep the projectiles and junk the rest.
Then reload the S&P with the commie projectiles for fun, and home cast wad cutters for business.