Loading with 215's over 210's

[Catfish]

There is no need for the hotter primer with the .308 case, but they can be used. From all I have read and been told since 1966 when I started loading my own, the you will get a presure increase with mag. primers, and you should drop 1 gn. of powder from the recomanded starting load when working up a load. I have never used a strain gage so I can go only on what I have heard and seen by looking for presure signs, but have done that many times and never had a starting load that was hot.
I did due some expermenting with velosities and primers this summer in a .22-6mm. What I found in that round was very interesting. Useing the same load except for the primer, I compaired 5 different primers. Different brands and some standard and some mag. Takeing the average of 5 rounds from each load there was only 51 fps., as I recall, from the fastest to the slowest with a round that was running between 3,450 and 3,500 fps. That was 1 gun with a round that is definately over bore.