Water capacity of different brands of brass

[Bull_Mtn]

I am running low on the brass I'm using for my .300 WSM. I have about 100 cases of another brand, some new, some once fired. I measured the water capacity (weight) between the two cases. The case I haven't used has a capacity that is 97% of the other case. Does this mean that using the same powder, primer and bullet, I must reduce the powder charge to 97% of what I have been using? Perhaps this is a little simplistic and I need to start from scratch, to develop a load with the different case. Any advice would be welcome.

 

[BoomFlop]

Anytime you change brass, powder (even lot#), primer (even lot#) and bullets it is always wise to reduce charge and work back up.

No easy answer.

Steve

 

[sedancowboy]

Like Steve said but I will bet that when you hit your current velocity you will be as good as ever.