I'm down to only one magnum rifle and am left with a large amount of magnum rifle primers. I would like to use these up in some my other rifles.

Question?? ...... When working up loads, is there any reason not to use a magnum rifle primer on a cartridge/powder combination that would normally call for a std rifle primer?

Since you're working up safety isn't an issue, so let the targets tell the tale. I've loaded more than a few 308 rounds with IMR 4895 and CCI 250's with fine results.

I read a an old comparison last week that suggested lower velocities (I think) in some chambers in some conditions..
Mule deer might know if anything more recent has been published.

SuperCub, if memory serves me, you have a 7x57 or two, I was happy with magnum primers and H4831 in my last one (haven't started loading for the current one yet.)

Yes, I do have a 7x57 as well as a few other middle of the road non-mags. Not having any luck with WW760 in this rifle, but next up will be 120gr NBTs and Varget. Not really a magnum primer load but going to try it with WLRM primers anyways. Have some H4831 and H & IMR 4350 down there as well so have some options. I really wanted that 760 to work in this rifle as I have a lot of it.

With ball powders, use magnum primers, even in something the size of your 7x57.
I've had good luck with them as well in the .270.

Try them, see what your rifles like.

Yup, I use magnum small rifle primers for H335 (ball powder) in my 223. A couple hang fires cured me of that.

With R26 I get more uniform results with magnum primers even in cases the size of the 308. It is unpredictable but sometimes you get an increase in velocity and sometimes a decrease. Not sure why but the primer may be starting the bullet down the barrel sooner so pressures are reduced.