Paul, I just got my 300 Win built on a defiance action with a 28" Broughton 5C barrel finished. Plus I load for 3 other 300 wins including my sons custom. Here is what they all liked with a 210 Berger.
Lapua 300 win brass.
Fed GM 215 M primer
H-1000 (start at 72 gr and work up) But probably in the 76 to 77 gr area you will see what you want foe velocity and accuracy. I am slightly over this and get 2995 fps from mine. My sons is at 77 gr and gets 2916 fps. neither are showing signs of pressure. But I have seen stock rifles show pressure at 74. This is why I say work it up and waych.
Seating is different with each rifle. I start at .040" off the lands then load a few at .050 and see if it likes it. If it does I keep going looking for the sweet spot. f it didnt like moving them farther off the lands I load some at .030 off lands and try that. Once you have a direction I test in .005 increments.
I took a nice 6x6 at 803 yards this year with mine and a 210 Berger.
I'm using 78gr Ramshot Magnum at 3.55"oal.
For saami oal you will need to reduce the load to 75gr at least.
Remember start low and work up.
I'm using Norma brass and fed215 primers