Thread: 300wsm primer choice

Greetings All,
I used Winchester Large Rifle primers in my 7mm SAUM and could not reach the velocities in the data for AR2213SC and AR2217 in spite of the 26 inch barrel. I had used the Winchester primers thinking they were hotter and I did not have any magnum primers at the time. Factory 150 grain loads chronographed 3,060 to 3,080 v the claimed 3,110 fps. Some 215 GM primers were aquired but I have not done much testing since. Later I read some pressure tested data on different primers in the 7mm RM and the .300 WM with H4831. From memory the 210 and 215 primers were much the same but the Winchester WLR primers gave high pressures, very high with the WLRM primers without any real increase in velocity. The tests appeared in different issues of Handloader 5 to 10 years back.
Standard primers may give good to excellent results in magnum cases (say over 60 grains capacity) on balmy testing days and fail miserably on a freezing winter day. Some have found this out the hard way.
Regards Grandpamac.