Do you resize virgin brass?

[mollerdan]

I resize virgin brass for sure. That is the only time I will leave the sizing button in my bushing die to center up the neck. Chamfer it and deburr, then load. Typically the lengths are very close to the same but if there is a big variance, I'll trim them all to equal the shortest piece.

The powder charge will change after it's been fired. Typically it will take less powder to achieve the same velocity when compared with new brass on it's 1st firing. My thought it that there is less brass movement when fired and that more energy can be utilized on pushing the bullet.

Do you know what kind of velocity difference you would notice between new brass and once fired with minimal shoulder bump and identical amount of powder? An approximate number is fine.