Each weapon will prefer a different load. Only way to find out is to shoot as many different bullet weights as you can.
All weapons exhibit a preference for one or more brands and projectile weights. You will have to buy as much as you can and shoot to get the answer for YOUR weapon.
You will have to shoot to find out.
Best to ask a gunsmith for assistance.
450
300 or so
Best left to a professional gunsmith.
300-500m
What is the price range for a browning patient 300 magnum rifle?
If your barrel is marked .300 Savage then you can shoot .300 Savage ammunition by any manufacturer. I do not know of a "300 Savage Winchester Magnum".
All firearms will show a preference for one or more brands and projectile weights. You will have to buy as many different types as you can afford and conduct a shoot off between them. Your weapon will let you know what it prefers.
300
how many numbers round to 300