Q: You seem to stress a high loading density as being an important factor in obtaining the highest velocity and best accuracy. Could you please explain this for me in more detail?
David Parsons
A: The criterion I have for a good load is that the powder fills the case to 85% or better. The less air space, the better.
Using a propellant that fills the case precludes a variation resulting from changes in powder position, making things more uniform.
As a general rule, the more powder you burn in a given cartridge without exceeding pressure standards, the higher the muzzle velocity.
Variables like bullet weight and case capacity determine the optimum powder burning rate or propellant.
A heavier charge weight at equal pressure indicates a slower burning powder, which generally means that there will be more area under the pressure curve. The area under the curve indicates the total amount of force behind the bullet prior to it exiting the muzzle.
A case full of powder eliminates air space and produces high performance, both of which are the criteria for a good load. However, other powders which do not fill the case completely will not be accurate.
How do you tell if a charge is compressed? Actually, it is determined by feel. If resistance is felt against the powder as the bullet is being seated, then you’ve got a compressed load.
I am not happy with loads that are heavily compressed as they sometimes force the bullet out of the neck, increasing the cartridge overall length so that the bullet either becomes loose or jams in the rifling.
When that happens I pick out a powder with 85-percent plus loading density which doesn’t result in a compressed load.
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