Primer seating depth and primer seating force

[mikecr]

Is there a reference available leading to SAAMI recommending 9thou primer crush?
If they recommend that -I suggest they are wrong. Don't do that

 

[Chaotik]

Is there a reference available leading to SAAMI recommending 9thou primer crush?
If they recommend that -I suggest they are wrong. Don't do that

On page 36 of the SAAMI specs they state:
"Primers to be seated flush to 0.008" (0.20) below face of cartridge case head"

 

[mikecr]

Yeah, 8thou below case head is not 8thou crush..
THIS CONCLUSION IS WRONG:
In conclusion, the anvil compression is the key variable and it is recommended that you compress the anvil at SAMMI specification (.008”) or .009”.

 

[WSnyder]

I am not sure how to measure primer cup height without anvil.

As I understand it, the anvil is ~.009 in height beyond the primer cup in his test of the CCI450's, which makes the primer cup height ~0.113 if the total primer cup (including anvil) height is ~0.122.

If the depth of the primer pocket is ~0.122 then it seems that one would be seating the primer maybe 1-2 thousands under the case head on a CCI450 primer, or bottom out the primer cup into the ceiling of the primer pocket?

In his test with the 450's to get .009" crush the cup is bottomed out in the pocket. One of his questions was if the cup position in the pocket had any bearing on accuracy. The answer was no it didn't, it was the amount of crush on the anvil in the pocket that was important..

 

[WSnyder]

Yeah, 8thou below case head is not 8thou crush..
THIS CONCLUSION IS WRONG:
In conclusion, the anvil compression is the key variable and it is recommended that you compress the anvil at SAMMI specification (.008”) or .009”.

Why is it wrong? In his two tests he found .009" crush to be the best with his combination which aligns closely to SAAMI maximum depth which is .008" (which would have resulted in ~.008" crush with his pockets and primers). He was using primer pockets and primers within SAAMI specs which suggests SAAMI was on to something in their recommendation. I previously posted a screenshot of his drawing with his dimensions he was working with and I'll post it again here.

 

[Bryan Z.]

I have to admit, I am completely ignorant about MacAllan 18.
I looked it up, now I'm curious.

Triple Cask Matured 18 Years Old - The Macallan Single Malt

Exquisitely and expertly married together, this trinity of spirits produces an exotic single malt with orange, velvety cocoa and wood spice flavours.

www.themacallan.com

The Macallan Double Cask 18 Year Old Single Malt Scotch Whisky

The Double Cask range combines the sweetness of American oak with sherry-seasoned American and European oak casks. These are hand-picked by the wood masters at The Macallan. The new American oak is first brought to Spain to be assembled and sherry-seasoned before the barrels travel to Speyside...

www.caskers.com

But not THAT curious!

CW

Nothing like that 18! Now you got me craving it!

 

[RegionRat]

I have to admit, I am completely ignorant about MacAllan 18.
I looked it up, now I'm curious.

No worries.
I've got you covered, but it will have to wait till the snow comes off up in Craig. I'll swing past on the way up.

 

[Webster]

On page 36 of the SAAMI specs they state:
"Primers to be seated flush to 0.008" (0.20) below face of cartridge case head"

I suspect the SAAMI spec has to do with safety and not accuracy. To prevent slam fires.

Added later:
SAAMI isn't an accuracy determining agency. It's about safety.

 

[Beiruty]

Some here are beating the bushes. Have you considered the variations in the primers' height?
I do not believe that the seating depth has anything to do with accuracy.
Here are the important things:
1) Seating slightly below the face of the cartridge case head
2) Primer ignition consistency. That is, the initial pressure generated with the primer being ignited.

 

[mikecr]

Some here are beating the bushes. Have you considered the variations in the primers' height?

My indicated K&M seater accounts for each primer height to each cup depth.
My testing has led me to 2thou sensitizing (crush) for Feds/Wins, and 5thou for CCIs.

I'm sure the notion of 8 or 9thou crush is damaging to pellets -if your pockets will even hold so much seating force without primers springing back outwards (or not if damaged). Normally, primer seating force is considerably lower than sensitizing force. That is why it's easy to seat primers to bottom by feel, but impossible to set crush by feel (with any precision).

 

[RegionRat]

I do not believe that the seating depth has anything to do with accuracy.

I will gently disagree (and will admit I am a little surprised).

We don't have to agree and nobody should take offense at the concept that primer seating to fine degree has affected group size or accuracy, or if they don't see it.

I will admit, not every system is capable of showing it when other dispersive parameters are drifting to a larger degree.

For my own outings, it just happened that the same levels that are spoken of by many here and a few of the ones on YouTube), have ended up being optimal at one or two thousandth plus or minus a thousandth of crush (assuming we all agree on the definition of crush).

While I was still working, I ran independent QC of primers of several kinds and batches. I can say that when you take a very close look at the issue in several fine dimensions, i.e., surfaces instead of single linear dimensions, the height of a primer anvil above the cup isn't without challenges.

They are often less than flat or parallel to the cup, and this is in addition to the dispersion on that average. Those errors in parallelism, flatness, imperfections, rough edges, etc., can account for a good chunk of that one or two thousandths, and that is before you can even say where the surfaces of the cup to anvil would average.

It should not be a surprise then, that it takes a little "crush" just to get the anvil down to first touching, then parallel, then preloaded, and then include a small fraction for deflection (Hertzian Contact Stress) in the tooling and primer components, before we see the optimal performance.

Since my own personal rigs have shown the performance changes with seating depths that either come short of this, or exceed it by very much as @mikecr is pointing out, my own opinion is what we are really doing is just trying not to screw it up. In different words, we are getting the anvil to flatten out and slightly preload to get them to their baseline design. There is no law or rule that says someone else may find a point short of this or beyond it that will give them an optimum.

Yes, they will ignite when short of this place, and also when they have been "crushed" much more, however the former invites timing delay and harmonic issues, and the second invites reliability and dispersion issues.

There are some specifications that require primer component testing. The tooling includes concepts that guarantee the activation energy of the strike tooling. The tooling is used to test exactly how much sets off a primer. When we seat those samples, we are very picky about their dimensional position to keep the testing fair.

As such, the opportunity to screw around with short seating and heavy crush, is something I couldn't resist.
You would be able to see the shortcomings of both conditions. It is just my own impression, that the baseline design is to flatten the anvil defects and just a little past that point, and stop... Not to come short, or to crush farther. I also think it isn't a coincidence that is where I get my own best performance.

Primer specs could be done better, as could cartridge brass specs, but committees are not a user to producer majority. When the manufacturers have too much control, sometimes things that should converge on an improvement will be traded off in a compromise to get anything done at all. Just one opinion and nothing to get worked up about... YMMV

Merry Christmas and Happy New Year!!!

 

[BoydAllen]

Because of this thread I decided to call CCI and Federal and ask about primer seating. I had to leave a message for both. CCI got back to me. Here is the deal. They want you to seat the primer to the point where the anvil legs are flush with the cup. The depth (untouched pockets) will depend on the brass. European brass has deeper pockets (I specifically asked about SR primers and their BR4s.) than American. Euro is CIP vs. US which is SAAMI. For SAAMI the range is .005-.008 below flush, for CIP which includes Lapua, the range given was .008-.012 below flush. He also said that because BR4s have a heavier cup it might take more effort to seat them to the recommended depth. Evidently the current Speer manual has a section on this. Do any of you have one? If and when Federal gets back to me I will do an update as a separate post.

 

[RegionRat]

Would like to hear what Federal says too.

I’ll be surprised if they tell you anything different.

The advice I was given has been the same.

I was given an education tour at the ammo plants as a youngster and they said the same back then, their baseline intent is to have the anvil feet touching as a baseline.

That sounds easy, but once you start thinking about the stats on the pocket depths, and the primer heights, you still have some inspections and homework to do.

Happy New Year!

 

[BoydAllen]

Would like to hear what Federal says too.

I’ll be surprised if they tell you anything different.

The advice I was given has been the same.

I was given an education tour at the ammo plants as a youngster and they said the same back then, their baseline intent is to have the anvil feet touching as a baseline.

That sounds easy, but once you start thinking about the stats on the pocket depths, and the primer heights, you still have some inspections and homework to do.

Happy New Year!

What he told me was they want the anvil pushed up into the cup to the point where the bottoms of the feet are even with the edge of the cup. Take a look at a primer. That is quite a bit deeper than just having the feet touch the bottom of the pocket.

 

[RegionRat]

What he told me was they want the anvil pushed up into the cup to the point where the bottoms of the feet are even with the edge of the cup. Take a look at a primer. That is quite a bit deeper than just having the feet touch the bottom of the pocket.

Okay, agree.

There is also the difference between the BR primer and the 450 for example. The cup heights are not the same on certain versions. The 0.109 versus 0.113 height of those cups and what they would consider their baseline can depend on the version.

On most primer batches, those anvil feet are not perfect and it can take a little body english to flatten them out into a plane that is parallel with the bottom of the cup, but in general that is on the order of a mil of uncertainty or less.

 

[mikecr]

It's typically not a manufacturer (much less some company nobody) who finds out what works.
It's the product USERS who do this.
That's us

Think about it; if the manufacturer knew what works best, wouldn't they tell us right up front?
The information would be on the box, right?
And of course WE would test it ourselves still.

 

[Chiquita]

It sounds like whether I use use the Cent21, primal rights, RCBS, Frankford or ... and whether I have Lapua, Remington, Starline... I need to test on my own and see the results anch chamge accordingly.

If I am happy and am winning matches with a Remington 15x fired brass and a good old hand primer without uniformed pockets, so be it.

If I am not happy then go up in price and test accordingly and rinse and repeat, rinse and repeat until I am a happy shooter.

I think that is what we are all talking about and trying to get across.

 

[searcher]

thing is the most important thing all those record holders have is something you cannot get with a credit card. My neighbor buys whatever golf equipment the current PGA pros are using, poor fellow has never broke 100 and never will. But if he ever wants to open a used golf equipment store his garage could stock one. No exaggeration, I would bet he has at least 25 putters if not more

 

[taylorw]

Ive ran primer seating depth tests with CCI BR2’s in 3 different rifles now (.243win, 7saum, 6.5x284).
I believe it was @mikecr that reported best results with the CCI’s at 6K crush?? but couldn’t find it when searching..
Out of the 3 rifles that I have tested from 0-8K crush, the .243win & 7saum had a window of 4-6K crush & the 6.5X284’s window was 5-7K crush so this is spot on with mikecr’s report and seems to be a common number with several rifles now.
Not sure if this has a noticeable effect but my brass is at a 2-2.5k shoulder bump, before testing the primer seating depth.

I just recently finished up load development with a 300saum imp and just set my crush at 5K, due to the other rifles having an overlap of 5&6K, being a common number, and it tuned up well.

I have also tested 210M’s one time in the same 6.5x284, with a different load/combo that works well, and didn’t really see enough of a difference to note it.
This is the only rifle I own that will tolerate the 210M’s so can’t provide more results than the one test.

I haven’t ran any SRP tests yet but plan to do so with a BRA and 6.5 Creedmoor.

 

[drop_point]

If I'm understanding correctly, the theory is that seating depth can be tuned almost the same as powder charge, but the primer seating depth affects where the powder will tune as well--just like seating depth can affect powder charge.

I have never used a fancy primer seater with the ability to control depth, but it does have my curiosity. If I start with a given primer seating depth THEN tune powder charge, will I ultimately have a more consistent load? Or if I come up with a powder charge with a hand primer, how much gain can I then get tuning primer seating depth? What about bullet seating depth? Will one ultimately end up with a similar load no matter which between powder charge/bullet depth/primer depth is tuned first? Which one should one start with?

Or does primer seating not matter at all in the real world so long as they are consistent and contacting the bottom of the primer pocket?