I would not use Magnum primers unless the reloading manual actually states to use it. Magnum primers burn hotter than standard and when using max recipes, this can put you over the maximum allowable Maximum pressure. The data that uses Magnum primers have been measure with pressure equipment. Without this equipment you are only guessing at Maximum pressure.
Cereal83, when reloading, every component has an effect on the reloaded round. Whether its primer, powder, bullet, or casing. Some things are not interchangable according to data published. For eg. You cannot substitue IMR powder for Hodgon powder even though the have the same numbers. Eg. H4350 and IMR4350. IMR burns hotter than Hodgdon in this case.
I ran across some test data a while back testing primers and pressures. Magnums primers produce a higher pressure and Winchester actually burns at the highest pressure, not Federal as a lot of people thought.
When reloading following the data exactly and don't start at maximum loads and you won't have a problem. Ensure you measure your cases with calipers and trim if necessary and measure finished rounds to ensure its within specs.