Looking for favorite loads with Win 748 and Hornady 170 gr fp. I am starting with 33.0 gr What is a good all around load for my hunting round in my marlin 336

This is my first attempt I also am using Fed 210 primers to start with. I have also heard that with this powder the Magnum primers work good is this true?

Many reloading manuals recommend magnum primers for any/all ball powders, and of course, WW748 is such a powder.

However, I have never used a magnum primer with any powder in cases smaller than 416 Rigby, and, IMO, a Fed. 210 will be all that you need in the .30/30 WCF.

A "maximum load" for that bullet and powder combination would be between 36 and 38 grains. I believe your charge of 33 grains would work just fine, if it is accurate. Avoid maximum charges in any reload you make until you know how to work up loads for individual, specific rifles. This is BECAUSE ALL RIFLES ARE DIFFERENT FROM ONE ANOTHER, and so are the maximum loads you can use in each one!

How do you know you are at maximum without any hi tech equipment? Is it in the cartridge? My reloading manual says max for this load and bullet is 36.3 gr. but online I found 32 for this bullet and powder. Also if I use the magnum primers would I use less powder generally? Thanks

Max charges will vary from manual to manual. Gun powder will also vary from lot to lot, sounds like you are on the right track. As eldeguello says above, you can vary the load a bit to see what works best in your particular rifle. The point of magnum primers is to be sure large powder charges burn completely and uniformly. I only use magnum primers in magnums myself. You should be fine with what you are doing with the 30 30.