Is there any research or history of loaders blending propellants to improve ballistic performance?
Hornady appears to be producing higher velocities without increasing charge weight in their Superformance ammo by using "progressive propellants." As best I can tell this means they are blending propellants with different burn rates in order to sustain peak pressure over a wider interval of time.
In theory this seems like a great idea: Since peak pressure of a homogeneous powder in a particular loading generally only lasts for an instant, we can stretch out the duration of peak chamber pressure by combining powders that reach their peak at slightly different times. (The longer the pressure peak is maintained, the longer the bullet enjoys peak acceleration, and the faster the muzzle velocity one would expect. One could also expect, as Hornady claims, that felt recoil would decrease since propellant efficiency is effectively increased, reducing rocket effect.)
In practice I imagine this would be difficult and dangerous to achieve without access to precision pressure-transducer barrels to work up the loads while being able to observe the timing and duration of pressure peaks. After all, even if you know the pressure curve of a single propellant in a particular load I doubt it's safe to conclude that blended propellants produce pressure curves that are just the sum of their curves in isolation.
Hornady appears to be producing higher velocities without increasing charge weight in their Superformance ammo by using "progressive propellants." As best I can tell this means they are blending propellants with different burn rates in order to sustain peak pressure over a wider interval of time.
In theory this seems like a great idea: Since peak pressure of a homogeneous powder in a particular loading generally only lasts for an instant, we can stretch out the duration of peak chamber pressure by combining powders that reach their peak at slightly different times. (The longer the pressure peak is maintained, the longer the bullet enjoys peak acceleration, and the faster the muzzle velocity one would expect. One could also expect, as Hornady claims, that felt recoil would decrease since propellant efficiency is effectively increased, reducing rocket effect.)
In practice I imagine this would be difficult and dangerous to achieve without access to precision pressure-transducer barrels to work up the loads while being able to observe the timing and duration of pressure peaks. After all, even if you know the pressure curve of a single propellant in a particular load I doubt it's safe to conclude that blended propellants produce pressure curves that are just the sum of their curves in isolation.