Question about using a large rifle primer in a 300 win?

[Patw]

I have a 300 win mag that I'm working up a load for. I'm shooting 190 Bergers and have 2 loads that shoot very well. One is with reloader 22 and the other with H4831sc, neither is a max load. I'm also using CCI-250(mag primers). I have seen more than one posting in the past stating that people are getting better accuracy using non-magnum primers in the 300 win. I have not tried this yet, but my concern is that I primarily use this rifle for deer and elk during late seasons in the Rocky's where the temp can be very low. Can anyone tell me if they have experience with non magnum primers in the magnum rounds and if cold weather is going to give me trouble with accuracy? Unfortunately, I live in California and really don't have much chance to shoot and work up loads in colder conditions. Any help would be appreciated.

Pat

 

[J E Custom]

I have a 300 win mag that I'm working up a load for. I'm shooting 190 Bergers and have 2 loads that shoot very well. One is with reloader 22 and the other with H4831sc, neither is a max load. I'm also using CCI-250(mag primers). I have seen more than one posting in the past stating that people are getting better accuracy using non-magnum primers in the 300 win. I have not tried this yet, but my concern is that I primarily use this rifle for deer and elk during late seasons in the Rocky's where the temp can be very low. Can anyone tell me if they have experience with non magnum primers in the magnum rounds and if cold weather is going to give me trouble with accuracy? Unfortunately, I live in California and really don't have much chance to shoot and work up loads in colder conditions. Any help would be appreciated.

Pat

I find that non magnum primers work very well in all but the very largest cartriges.

In cases with a powder capacity of less than 90 grains I actually have lower SDs than with
magnum primers.

The velocity is slightly higher with the mag primers but not much and the lower SDs of the
non magnum primers makes it more attractive to me.

Also the powders you mentioned are not that hard to light in cold weather.

With the very slowest powders, magnum primers are sometimes needed when case capacity
exceeds 100 grains.

J E CUSTOM

 

[djtjr]

I too like the non mag primers in most cartridges up to and including the 338 lapua. One time I ran out of mags and built up loads with the standard and found group sizes shrunk and grew the same relative to charge weight but that the non magnum primers groups were exactly half the size as the ones for the same charge weights with mags. I use the non mags in virtually all but the most extreme condition gun, and think you will find the same.
Best,
Don

 

[Patw]

Thanks for the input, I thought I had seen others post similar info. Would you both just change the primer and leave everything else the same? The two powders I listed are shooting good, one is slightly under .5 MOA and the other is slightly over .5, but I don't see any reason not to improve if possible! it certainly won't matter in hunting, but I also enjoy punching holes in paper.

Thanks again for the input
Pat