Some of this I find quite interesting. I'd like to learn more about which powders typically "pressure up" different/sooner/ later than others. I have a 338SS and with my crappy RP brass I have seen pressure signs with some powder earlier than with others and with different velocities. I'd like to learn why so I can narrow down my powder choices for a variety of reasons; case life, throat life, temp stability, efficiency, safety, etc etc. I will soon be getting Rich's ADG brass and am interested to see the difference with some of my current loads that showed pressure signs.
I can give you an example that stands out quite considerably just in case shape/caliber size.
The 300WM thrives on slow powders like RE25/6, H1000 and Retumbo.
The 338WM thrives on powders like RE19, H4350 and H4831.
The 338 seems to top out with powders like RE22, where RE19 often beats it for velocity,
and powders like H1000 just are too slow to work correctly.
There is a general rule of thumb that straight walled or minimum shouldered cases work best with medium burn powders. For example, the 375 H&H, 375 WBY and 458 Lott all perform best with powders like H4350, W760/H414 and RE15.
The reason for this is due to the free and smooth flow from case body to the neck, the powder is not held back in the case as it burns and is following the bullets transfer into the rifling, changing HOW it burns. A slow powder, which I have tried, does not burn completely or in a progressive fashion. Simply put, it fizzles out as the gas cannot fill the void the bullet is leaving behind it. Powder needs pressure and heat to keep burning inside a barrel.
Cheers.
