Re: 5010 powder
I would not use 5010 in my 30/378.
I know of one 30/378 that was shot out in 600 rounds using it.
It is a large stick powder that likes to eat barrels and I'm NOT kidding.
Get some H870 or WC 872 and it will do just fine.
Email me for load information and let me know what action and barrel length you have.