First research John Barsness on the topic. There are a trio of general gun gack books as well as a smaller reloading book, a newsletter and more. An early treatment ~ 15 years old is an article on Loaddata.

I emphasize that as with any other source of reloading data the latest version should always be controlling.
Quote
....This means a load that produces a very safe 58,000 psi with one primer can produce an unsafe 70,000 psi with another—and often there’s no way for the home handloader to tell the difference.....
Emphasis added. There is some information in traditional pressure signs but so much noise as to make using traditional pressure signs meaningless. A rifle fired with over pressure loads long enough will eventually fail with a load well within the pressure range considered safe enough without abuse so working up in a range of useless pressure signs doesn't do much good.
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Quote
.......What all this means is that we should be very, very careful about which primers we use. The safest technique is to use the exact same primer listed in the loading manual for any load. Unfortunately, this means stocking almost every primer made, an expensive proposition. Instead I generally start with either CCI 200 (standard) or Federal 215 (magnum) primers in rifle loads. Both of these primers are among the mildest of their type so should produce safe pressures....
again Emphasis added. I read this to say that at the time of writing Federal 215 was among the mildest of magnum primers. I do not read this to say that at the time of writing Federal 215 was milder than other non-magnum primers. I certainly do not read this to say that 15 years after the date of writing the assertions are guaranteed to be still true.

But swapping in a Federal 215 is presumably swapping a milder primer into the load with Winchester and therefore likely safe enough - is gun is dangerous.

Again, I hasten to add there is more recent material out there than the quoted material and the more recent material should control any use. Once into wildcatting territory it pays to read it all.

It should go without saying but I'll say anyway that nothing has changed to make swapping primers any safer.