Little Informal Primer Test

[RL338]

The other week I did a primer test to see if there really is a difference. I used the 375 Wby and 270gr Speers that I backed off the load a little so there wouldn’t be any pressure surprises.

Results are as followed.

The CCI had a spread of 60fps which is somewhat odd. These were fresh from SW this summer. I wonder if running around the clock has brought them a quality issue. These are what I was using in my 338WM , maybe that was causing an accuracy issue for me. I firelapped that barrel and did switch primers and the accuracy did improve.
I’m going to run this test again in the 338WM instead to see if there is a difference.

 

[JD338]

Interesting results

JD338

 

[DrMike]

While perhaps suggestive, the numbers tested are really too small to make a conclusion. What might be a more conclusive test would be to build sets of ten cartridges, all built at approximately the same time, holding all the components as near identical as possible. Still, interesting.

 

[RL338]

I totally agree with a larger sample , my take away was to see how the 50 year old Alcan primers would stack up. I have several different bullets loaded up with them in 375 Wby for now.

 

[NYDAN]

Those 50-year-old primers held their own against the newer ones.

 

[RiverRider]

I'd try it again with brass all matched for volume and with case necks annealed, and like DrMike says, use larger sample sizes. Even if those were not factors in the results you see, it could be that the charge weight of that powder just isn't optimal for the primer and it's also possible the powder type is not optimal for the primer.

Ten rounds of each load is a lot of components, but proper sample size is imperative for experimenting...and ten rounds really isn't that large a sample size.