Re: Standand match primer in an ultra mag?
I used some CCI BR-2's in my 300 RUM a few years back with H-1000 and 200g AB's.
Initial load testing was in about 40 degree weather. Igniting 92-94g of H-1000 didn't seem to have any effect with the standard BR-2 primer. Accuracy was the same or better then Fed 215's I had been using. Velocity was the same or maybe at most 50fps slower.
So I decided to load them up and take them elk hunting. Elk hunting was about 0 degrees and that was enough to make it go from no problems to about a 1 second hang fire every time I squeezed the trigger.
Cold weather will definately play a factor in it. I would say if your above freezing, they should work every bit as good as a mag primer. But below freezing, the hotter spark is definately needed.
Hope this helps some.