I bet if you put it on a chronograph at that speed with 2400, you'll find that velocities are all over the place.
I really like 2400,....it's one of my favorite propellants, but it's made to *pop*,...as is any propellant Blue Dot or slower.
I'll admit,...it's kind of a funny cartridge,.. but even so you're talking about low pressures.
I'm guessing that the most consistency you're going to find with it at the velocities you're looking for will be in the medium/fast handgun propellants.
Basically, it's a slightly skinny, heavy .38 spl.+p.
I'm still thinkin' that if you get slower than Blue Dot at the velocities/pressures you're looking for, you're going to get erratic ignition,...which is going to cause erratic pressures and velocities,...and consequently, erratic accuracy.
Propellants start getting very particular about pressure once you hit the Blue Dot burning rate.
