The Russian Mosin Nagant Forum

I made up some ammo using 200 grain lapua d166 bullets, ppu cases, magnum primers, and 3.1 cc of h414 powder. It shot well when I loaded it with my lee classic loader but these ones were loaded with the lee hand press and 7.62x54r dies, so I am expecting better results. Case length overall is 3.005≈ The neck was also sized down to 308 to help hold the. 310 lapua bullets better.
I'm expecting it to perform very well in my m39's.

Any reason you are using magnum primers?

The h414 powder is flake/ball and has a hard time igniting in these cold Maine winters with normal primers. I would get hang fires 8 out of 10 times. So I switched to the magnum primers for the hotter and longer burn time and the issue was resolved. plus, since I am using the lee dippers as compared to a powder scale, I gain a little bur of extra velocity due to more consistent powder burning.
A very long way of saying they work better. Lol.

That is what I like to hear. Back up your info with the fact that you have done it, not just heard it on the internet. Good report Johnny.