Re: Vitavourhi Powder?
TomVan, I am using Vihtavouri N550, N560, N165, and N170 in various rifles, and found that these powders work well, and have heard good reports about most of the other powders in their range.
The Vithavouri powders most suitable for your 300 RUM with the 180 & 200 grain bullets would be N165, and N170.
I also agree with the advice of Brianb in the previous post. Chronographs are now relatively cheap, and having used various chronographs for over 30 years, I have found that they are an important tool in the task of working up loads with various powders towards maximum pressure, and for accuracy.
I recommend that you that learn the art of working up loads in your rifles and become self reliant, rather than rely on reloading manuals where the data often varies significantly from one manual to another with the same powder/bullet weight. Good luck, Brian.