Thread: Primer testing methods

How are people testing primers? I've seen several methods:

1. Shoot a 10 round ladder test over a chrono and look at the stability of the curve.

2. Load 3 rounds of your preferred charge with a different primer: -0.5gr, +0.0gr, and +0.5gr. Shoot them over a chrono and see if ES/SD improve.

3. Shoot groups with each primer and compare the sizes.

And finally some more questions:
What is your preferred method?
Will a specific powder have a preferred primer?
Is a good primer a good primer and will work well regardless of other variables?
Can a primer with poor stats group better than one with superior stats?

Test parameters:
1 - Make sure primer is not Winchester.
2 - Pull trigger on loaded case, if it goes bang, test complete.

@Magnetite, kinda depends on what you want to achieve.

For most shooting (service rifle, gongs, hunting) I just load using Federal.

When I shot fullbore and was looking for the last ounce off accuracy, I did full load dev with 3 different primers. They can make a surprising difference to your SD values. RWS primers were by far the best I tested, followed by Fed Match and CCI BR.

In general, powder and or primer will give you speed consistency. Seating depth gives you group size variation within that.

Originally Posted by 257weatherby

1 - Make sure primer is not Winchester.

Please elaborate on step 1.

Originally Posted by Magnetite

Please elaborate on step 1.

Couple years back Winchester primers had some quality control issues. Lot of people ended up with gas cut bolt faces.

Use them at your peril.

Just hit it with a hammer

Originally Posted by ebf

Couple years back Winchester primers had some quality control issues. Lot of people ended up with gas cut bolt faces.

Use them at your peril.

+1 would never use a Winchester primer again.

Federal match in SR and LR. CCI 250? mags, job done.