Why different primers

[RichCoyle]

Here is a round robin test of different brands of primers. I should have included my regular primer, the Winchester WLRM primer. It normally shoots groups of 3/8" to 1/2" at 100 yards at an average velocity of 3,665 feet per second. Round robin means I fired one shot at the first target and then one shot at the second target and one shot at the third and then two at the fourth target. Then one shot at the third and one at the second and two at the first and then back towards the fourth target. My theory is each target gets the same amount of dirty barrel. You know, ignorant prejudice. I didn't fire the third shot at the first target because the first two were too far apart.

I noticed the third shot always opened up the group.

 

[cajun]

This is one of those cases where I think you would need more data to say for sure.

 

[Rich Coyle]

Thanks. What data?

 

[cajun]

Thanks. What data?

I guess I meant to say more data points. One 3 shot group is a small sample size. However given where you are with the primers you are using I'm not sure I see anything here wasting components on.

 

[Mikecr]

What you're doing is an abstract, and you didn't get lucky with it.
Couple things in play:
1. Changing primers changes load results. This, especially if testing from a powder node.
2. Any primer likes an optimum striking -for that primer. Your striking is the same for all.

Primer swapping should be done away from a powder node, so that you're not coming into or out of a powder node.
You want to see ONLY which primer likes your striking the most.
Then develop a load with that.

Otherwise, you can pick ONE primer, and adjust striking for best from it.
Then develop a load with that.

 

[David_h]

What you're doing is an abstract, and you didn't get lucky with it.
Couple things in play:
1. Changing primers changes load results. This, especially if testing from a powder node.
2. Any primer likes an optimum striking -for that primer. Your striking is the same for all.

Primer swapping should be done away from a powder node, so that you're not coming into or out of a powder node.
You want to see ONLY which primer likes your striking the most.
Then develop a load with that.

Otherwise, you can pick ONE primer, and adjust striking for best from it.
Then develop a load with that.

Makes sense. Which primer(s) do you use to find powder node(s) so as to avoid nodes when comparing primers?

 

[MagnumManiac]

I test primers just like I test seating depth, outside of a node. I test different brands AND types, then when I find THE one, I test primer depth and amount of crush from .001" below flush with anvil through .001" intervals to about .008" total. With this known, you can almost certainly seat your primers the same depth in different loads and be very, very close to ideal without much tweaking.
Often, brand makes as much difference as does type. Magnum primers don't have to be used in magnums and standard primers in magnums are just as often more precise than magnums. Magnum primers often work best in SRP brass too, they do in my 22-250, 22-250AI and both of my 6.5x47's.

Cheers.

 

[Mikecr]

Which primer(s) do you use to find powder node(s) so as to avoid nodes when comparing primers?

I use QuickLoad to put me between what I suspect as upper/lower powder nodes.
I used to validate my suspicions at http://www.reloadersnest.com/rifle.asp
Later, I'll validate with my actual findings.

I use the same between node charge for my full seating testing.
Both tests performed while fire forming new brass, seating 1st.
With this, it should be easier to clearly see improvement, or detriment.

 

[Sierra6]

What specific result are you looking for??? In other words are you looking for group size, ES/SD, vertical or something else???
I've usually picked a primer based on feedback for that particular cartridge and powder BUT that is not the best way. Thanks in advance

 

[Mikecr]

I test primers just like I test seating depth, outside of a node. I test different brands AND types, then when I find THE one, I test primer depth and amount of crush from .001" below flush with anvil through .001" intervals to about .008" total.

I can tell you where best crush is: 5thou for CCIs, 2thou for everything else.
This, I set directly with an indicated K&M.

The testing, especially striking optimizing, goes better from the git-go with that crush standard in-place.
Otherwise, it's more concealing of what you're after.

 

[Mikecr]

What specific result are you looking for??? In other words are you looking for group size, ES/SD, vertical or something else???

You can actually use either SD, or grouping, while between nodes. Both should be ugly but getting better or worse.

What this industry doesn't get is that primers and seating are best approached as prerequisites to tuning (NOT tuning in themselves).
For tuning you have powder node, barrel node, and system (rest, balance, hold, etc.).

 

[Sierra6]

I originally was told or read was primer testing was a small and factor and only necessary if seating depth and powder charge aren't coming together. Yet ignition is huge IMO and going from a a magnum to non magnum in my 7SAUM was a significant improvement and consistent seating depth of primers has shown me otherwise. Thank you guys for the info and bump to do more testing with primers.

 

[MagnumManiac]

I originally was told or read was primer testing was a small and factor and only necessary if seating depth and powder charge aren't coming together. Yet ignition is huge IMO and going from a a magnum to non magnum in my 7SAUM was a significant improvement and consistent seating depth of primers has shown me otherwise. Thank you guys for the info and bump to do more testing with primers.

This is a direct result of changing start pressure. A uniform start pressure is the basis of an exceptional load. The Pressure Trace taught me this very quickly, erratic ignition is very poor for a consistent load.

Cheers.

 

[MagnumManiac]

I can tell you where best crush is: 5thou for CCIs, 2thou for everything else.
This, I set directly with an indicated K&M.

I do the same with my K&M, but now use the Primal Rights due to my hand issues.

Cheers.