I've read where some guys are having some "issues" with Nosler brass. I have not. For the 300 RUM, I suggest Federal brass, if you can find it, and/or Nosler brass. If Norma is available, bite the bullet and spend the money on it as first choice.
My opinion: Remington brass is ok but not great quality.
I had a very easy time getting all 3 of these powders to work very well with the 180 Scirocco and the 200 AB: Re25, H1000, and Retumbo.
I just spoke with Mr. Hodgdon this week and discussed how Retumbo is his powder of choice for its repeated consistency lot to lot, temp stability, etc. Regardless, I suggest you buy 5-8 pounds of the SAME lot # so you should be set for a long time.
I've not put any Barnes bullets through this RUM yet as I had such great luck with the 200 AB and 180 Scirocco right from the get go. I have a lot of 180 TSX and TTSX on hand.
Oh, I did try some 180 ABs too but the tips were breaking off so Nosler sent me some 200s so I never finished testing the 180s.