Temp sensitivity and the magnum primer…

[762willdo]

Has anyone done any testing in this area? I thought I read on this board years ago about someone who claimed using a magnum primer mitigated the temp sensitivity issues but I can’t seem to find it…..

 

[searcher]

That would be interesting reading, seeing how many magnum primers really aren't any "hotter" than non-magnum primers. Those that are could better ignite certain powders - so I'm sure there would be reference to particular powders. From the testing I have done (small primers only), there was only a small deviation (around 40 FPS) between a number of the various primers with the one powder I used in my test (which in itself could be considered quite inconclusive). When using some powders which are temperature sensitive, a change in powder charge that creates a greater change in velocity than that is often required - so I'd be inclined to not believe that a primer change would "cure" temperature sensitive powders. I can't put my finger on the larger test data at the moment - but here is another example of a much smaller test I did on a .223 test, using Lake City brass, 50 V-Max bullets and 22.6 grains of Accurate LT32 powder through one of my A/Rs.

Tula .223 primer 3,098 fps sd 24
Tula .223 Mag 3,096 fps sd 34
Fed A/R Match 3,072 fps sd 34
Rem 7 1/2 3,083 fps sd 15
CCI 450 3,091 fps sd 26

As you can see from the difference in extreme velocity between these primers (26 fps) - any change in primers would not likely overcome a change in temperature sensitive powder. My larger test pretty much had similar results. This is a load I use in both 100 degree temps in summer and 30 degree temps in the spring. I alter my powder charge 8/10 of a grain between summer and spring to maintain similar velocities - which a primer with the above velocity differential could not replicate by themselves. And the Accurate LT32 powder is not nearly as temperature sensitive as other powders I use (Like Reloader 7 which requires 1.3 grain increase/reduction in another bolt gun using the same bullet/brass)

It would be interesting to see what kinds of results others have seen doing such comparisons.