Primer vs Pressure

[RDA 226sig]

Ran some test loads through a new rifle and they shot well but the primers are dimpled around the firing pin a bit. (See the 300 WSM primers below) However, they are not flat on the edges like I would expect from a hot load and the charge is well below max. (This was the start load) I have also attached a photo of some 338 brass that has primers from the same lot and it is clear that the edges have flattened. I am thinking the dimple is mostly due to the shape of the firing pin hole but thought I would post for opinions.

http://i321.photobucket.com/albums/nn390/RAD1768/DSC_0214.jpg

http://i321.photobucket.com/albums/nn390/RAD1768/DSC_0216.jpg

 

[USSR]

...I am thinking the dimple is mostly due to the shape of the firing min hole...

And you would be thinking right.

Don