Most dealers don't like stocking 300 wbys in nosler partition loadings because they are so expensive and most guys settle for the 180 grain hornady bullet they load in their ammo. Norma brass used in their loads just drives up the price of their ammo.
Couple of different ways to get ammo for that gun. I would try Federal who makes 3 loads for it all 180 grain loads and all should do the job on Elk and Deer with zero problems. Hornady also loads a 180 grain load with the same bullet Weatherby uses(Spire Point) but with Frontier Brass and usually a lot cheaper. I have used Spire Points only once in a 300 WBY on Elk and it was a good sized cow at about 300 +- 25 yards. Cow dropped at shot and got up and ran about 50 yards. I thought the blood trail was minimal but it went thru her ribs and out the other side and killed her so I guess it was OK just maybe not as much expansion as I wanted. I also used it on a Mule Deer that hunt and on a few whitetails when I got back home and it did the job. I think even Remington still loads for it but not sure what they are loading into it. I have only used Weatherby and Hornady ammo in my 300 and was satisfied with both brands . Never did get to try out Federal.
If you want checkout
www.dnrsports.com www.midwayusa.com www.natchezss.com for availability.