Velocity and pressure

[wareagle1]

Should there be any difference in velocity or pressure when I PFL resize(60% of the neck) vs FL resizing. I was just wondering because it seems that less surface area of the neck gripping the bullet might affect velocity and pressure. Also, it could have been my imagination, but there seems to be less recoil with my PFL sized cases.

 

[Ol` Joe]

The very little the neck tension retards the bullet doesn`t make any difference in pressure or velocity we can notice. The chamber and bore volume have the most effect with the bullet being retarded by the neck tension haveing very little effect on peak pressure that we likely can measure. I`ve shot loads over a Pact crony with cases sized partial, full and neck in more then a few cartridges and never have I noticed a velocity change that was outside the extreem spread I`d found with FL sized cases when useing partial/neck sized ones. I have never tried measuring pressure with both sizeing methods though employing my pressure trace unit, I can`t honestly comment on how that is affected. I doubt any change there is much, though this is just opinion.

The bullet being jammed in the leade will however cause a change in the rise time of the powder burn and may cause problems if you don`t work your load up with the condition from the start.