Slim,
SOME powders produce the highest velocities in SOME cartridges. While some of those are newer powders, some aren't--and so far there's always some other compromise being made.
"The" Superformance powder in various Hornady factory loads is actually several different blends of similar powders, each formulated to produce the most velocity in a specific cartridge, or even a certain cartridge/bullet combination. The Superformance sold to handloaders is the .30-06 blend, and yes, it does produce more velocity in certain specific instances. But that's been going on for a long time, with a lot of different powders.
If you check out loading data for various cartridges, there are always certain powders that produce the most velocity in certain combinations. IMR4350 is now 75 years old, and its still at or near the top for certain applications, despite being a single-base powder.
A few years ago Reloder 17 was supposed to be the new magic super-velocity powder. That lasted until Alliant published actual pressure-tested data. While RL-17 does do very well in specific instance, so do many other powders. In fact, it turned out that even some of Alliant's other powders beat RL-17.
One other interesting fact that can be learned from actual pressure testing, instead of the pressure guessing many handloaders (like you) depend on, is how often traditional "pressure signs" don't show up until 70,000 PSI or even 75,000 psi. And that's in temperature- and-humiditycontrolled laboratories, not out in the real world where it isn't always 70 degrees, and the bore may have some moisture inside.
That's exactly why SAAMI standards leave some wiggle room. They don't want some handloader running pressures up to the absolute max, and then when conditions change their "safe" load somehow isn't as safe as it seemed the day they worked it up.
