For the most part if you are shooting the Magnum bullets at paper or steel targets, standard pistol primers should do the job. If you are using the bullets for self defense or hunting, then use the primer specified in the loading data tables.

With some powders I find little to no velocity change, but with certain other powders (specifically Titegroup) the Magnum primers make a big difference.
Since the Magnum primers are really the same price (or close) I would generally use what the tables say they tested the load with.

Chief38