If you load the same bullet and charge in a case that it say fills to the base of the neck, and in another that has more capacity and therefore excess space leftover, what is the effect on velocity? Pressure?

Specifically, I've been toying with another 17 caliber rifle, maybe a 17 Fireball or 17/222. I already shoot a 17-22/250 with 30 grain bullets and 20 grains of RL7. I haven't chronographed it. Laying awake at night it gives me something to ponder, what would be the most efficient case with the same load and what would each act like?

Just never connected the dots. Thanks for your thoughts.

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Generally, both will decrease.

+1

The most efficient with a given powder charge is the smallest case that keeps max pressure below a certain limit.

Thank you.