There is probably no other subject than shooting in general and reloading in particular, to have so much hogwash (oops, I mean theories) attached to it. Primers is a good example.
--You have to use magnum primers with ball powder.
You have to use magnum primers in cold weather.
You have to use magnum primers in big magnum rifles, for sure with ball powder and of course a big magnum, in the cold, with ball powder!
You have to work up your load again when you change to a magnum powder, and on, and on and on.
Boomer lives in a cold area, so last year we talked him into doing a cold weather test, using magnum primers and standard primers, in various rifles and some using ball powder and even a big magnum with ball powder.
I have taken the liberty to repost the results of his tests, done a year ago.
http://www.canadiangunnutz.com/forum/showthread.php/1042057-Cold-Weather-Primer-Test
Here are the results of his test.
So I'll start with the test parameters. What I was looking for was ignition problems, differences in average velocities, and differences in extreme spread. To ensure it would be the primers that resulted in velocity variations, I took the trouble to keep bullet and case weight to within a quarter a grain for each 5 round group. All of the cases were trimmed and chamfered, and the primer pockets were uniformed and the flash holes uniformed and de-burred. I wanted to test both ball and extruded powders, both fast and slow burning powder, in small, medium, and large capacity cartridges.
The test did not go without a few hitches. The first problem was that the Oehler P-35 didn't read the bullets fired from my SAKO .222 magnum, which was disappointing, so there is no .222 Magnum data to report. The Chronograph failed to read one of the magnum primer loads in the .30/06 and failed to read a magnum primer load in the .458. The .270 data showed lower velocities than I would have expected for a 130 gr bullet, running in the mid 2800s then the first 3 magnum round had little spread, but the last two increased the ES to 180 fps!!?? I hadn't worked up the load however, but Bruce wanted me to have the test include 60 grs of H-4831 under a 130, so that's what I put together.
Here are the results minus the .222 Magnum . . .
.270 Winchester
Ruger Hawkeye 22 inch barrel
Winchester brass
Winchester PP bullets
60.0 gr H-4831SC
CCI LR BR-2 Primers....................Remington 9.5M LR Primers
2837..........................................2841
2830..........................................2840
2833..........................................2842
2793..........................................2953
2814..........................................2772
Average 2821, ES 44...................Average 2849, ES 181
.30/30 Winchester
Winchester 94 NWT Commemorative 24"
Winchester brass
170 gr bullets, unknown make
30.0 grs IMR 3031
CCI LR BR-2 Primers....................Remington 9.5M LR Primers
2070..........................................2026
2065..........................................2052
2021..........................................2028
2044..........................................2087
2071..........................................2052
Average 2054 ES 50....................Average 2049 ES 61
.30/06 Springfield
Brno ZG-47 24" barrel
Remington brass
180 gr Sierra BT
58.0 grs H-100|V
CCI LR BR-2 Primers....................Remington 9.5M LR Primers
2775..........................................2768
2756..........................................2783
2827..........................................2773
2758..........................................2764
2727..........................................0000
Average 2768 ES 100..................Average 2772 ES 19
.375 Ultramag
Brno 602 22" barrel
Remington brass
270 gr Hornady Interlock
92.0 grs H-100V
CCI LR BR-2 Primers....................Remington 9.5M LR Primers
2948..........................................3015
2967..........................................2991
2973..........................................2976
2923..........................................2983
3012..........................................2963
Average 2964 ES 89...................Average 2986 ES 52
.458 Winchester
Winchester M-70 Express 21" barrel
Winchester brass
500 gr Matrix
76.0 grs H-335
CCI LR BR-2 Primers................... Remington 9.5M LR Primers
2059..........................................2003
2097..........................................2066
2113..........................................2067
2054..........................................2074
2091..........................................0000
Average 2082 ES 59...................Average 2052 ES 71
So that's it. Some of the readings such as the last two magnum primer velocities in the .270 make me wonder if a combination of the low morning light and the atmosphere full of ice crystals didn't produce some false readings. Perhaps that was the reason for the lack of readings with the .222 magnum, and the missing reading in the .30/06 and the .458. Anyway, its interesting stuff, and I think it shows that although I still prefer to use magnum primers, there is no practical ballistic advantage in doing so. I was really surprised by the .458 results, as the combination of ball powder, a powder charge greater than 50 grs, and extreme cold should have made magnum primers a distinct advantage over standard primers. I did not observe any hang fires in the course of this test
