Re: Case head expansion.
I shoot a 240 Wby.
I am not sure case head expansion means anything in a 240Wby. Norma brass is relatively soft and hot loads will loosen primer pockets before anything bad happens. Some of my loads are so hot the primers are left in the action after I shoot.
A lot depends upon how your chamber was cut. I had a factory spec chamber with freebore in a Douglas barrel and took that off and had a minimum SAAMI chamber with no freebore cut in a Spencer barrel. Brass that had been shot with only moderate loads in the factory style chamber would not fit in the minimum SAAMI chamber because the belt had expanded by .001 inches.
I am not familiar with the powder you mention so have no understanding of amounts and pressure. I am using RL22 in a 30 inch barrel with 115 grain bullets.
The Smokin Fur Rifle Club