I was just looking through the yellow Contender reloading manual last week regarding this very subject. I was getting ready to load some 7-30 rounds when I realized that I did not have any standard large rifle primers on hand, but did have several hundred LR magnum primers on hand. I decided to look to see if anyone recommends using magnum primers with WW748 powder.
The Contender loading manual shows using Federal 210 (standard large rifle) primers in all but the Speer portion of the 7-30 Waters data. Since I havent used Speer bullets in my 7-30, I never really paid much attention to their section in the 7-30 loading data. My search did confirm that Speer is the only bullet manufacturer who recommends magnum primers with WW748 powder. Since I am only loading Hornady and Sierra bullets, I chose to stay with their loading data and did not switch to the magnum primers. More importantly, I have never had any ignition problems with 748 and standard primers, nor do I find any unburned powder residue in the barrel or case.