Re: Primers .... Magnum or Standard
I think so? What you should be aware of is the intensity of the primer discharge will affect, (somewhat) the burning rate of your powder, in most cases, the powder will burn faster than what it should, so, if you were using IMR 4350, it could burn like 3031, with a mag primer. I just made that up, and it is a way extreme example, but the trend will be faster and if that's okay, suits your purpose, then it doesn't matter much. But, it could result in degraded performance as far as velocity?
I'm trying to answer your hypothetical question. You never mention the powder, so who can say if the magnum primers would help or not hurt the performance? Primers are cheap, don't use them in a 308, if you don't have to because you might find very little data for that case, powder, bullet and a mag primer.
I know a few predator hunters, (thousands, actually) but some live in Canada, and they might have a large supply of H380 and hunt in subzero conditions. Hypothetical only, I don't know that, for a fact? Anyway,it would make sense to use magnum primers or suffer rather degraded performance/velocity, and there goes your ability to hit what you are aiming at, at far ranges. That is an example of why you would want to use magnum primers when they are not needed, in most applications. Unless, (of course) you are trying to light 100 grains of slow burning powder?
It's not that big of a deal, as you say, but I would end it at this point and use the data as comparative, and get back to a standard large rifle primer; were I you. BB