Hardest cup, softest cup?

[dahermit]

...CCI has the hardest cup, Federal primers the softest...

I am quoting something that I wish a little discussion on. I took that quote fragment from another thread inasmuch as I did not want to hijack that thread.

It is my understanding that the sensitivity of the different primers is not due to the "hardness" of the cups, but due to the different primer compound used in them. As I remember from an article on the subject, there are two different formulas for priming compounds; "Normal" and "Standard".

As I remember that is in part why Lee would not recommend Federal Primers in their in-line primer tube tools. Aside from being perhaps more sensitive, the Federal primers produced more catastrophic results when detonated en mass.

I remember Lee being jumped on for being bias against Federal primers...even after he explained it was not bias, but a safety issue.

So, those who have better credentials in the matter, or have done some hardness tests on the brass cups (seems that the hardness of the brass alloys could be measured on spent primers without too much difficulty), what makes Federal primers more sensetive than CCI; the priming compound or the cups?

[WESHOOT2]

Both.

[Brian Pfleuger]

There's absolutely no question that Federal pistol primers are "softer" than CCI.

Whether its an alloy difference or thickness, I can't say.

Federal primers will severely flatten, mushroom and pierce is my G33, with loads from below starting to over max. I tried SP, SP Match and SP Magnum. All do the same thing.

CCI primers, never has a single one done any more than slightly flatten with hot loads.

[Slamfire]

There is very little about primers in the public domain. Primers are not as simple as we think, and I don’t know all the little issues with them, but searches of DTIC documents show there are several ways to vary primer sensitivity.

I understand Federal makes a mil spec primer, it may not be available to the public, what I heard it has a thicker “harder” cup. A thicker cup, even with their more sensitive primer mix, would result in a less sensitive primer:


Finite Element Modeling of Primer Impact to Understand the Dynamics of Misfires

http://www.dtic.mil/ndia/2011ballistics/12080.pdf

What is in the primer mix can be varied to alter sensitivity.





I wish there was a book on primer making and all the different ways and techniques to make primers more sensitive, more consistent, dwell times, temperature sensitivity. But in the US, all that information is owned by commercial primer manufacturers and they are not telling anyone anything.

[William T. Watts]

The Federal LR primer has a softer cup and I use these in my lever rifles, CCI LR primers are noted for a harder cup which make them a better choice for my bolt action rifles. There is another difference between the various makes of LR primers that isn't talked about much, Federal and CCI primers are a full .001" larger (.211") than Remington or Winchester LR primer (.210"). William

[SHR970]

dahermit wrote:So, those who have better credentials in the matter, or have done some hardness tests on the brass cups (seems that the hardness of the brass alloys could be measured on spent primers without too much difficulty), what makes Federal primers more sensetive than CCI; the priming compound or the cups?

There is a problem with the underlined idea. As you bend/ deform/ hammer brass it work hardens. Taking a spent piece of brass that has been deformed more than another will yield different results given that identical lots of brass are used. Now let us assume that the alloy and thickness between the Federal and CCI primer brass are both different. Let us also assume that the Federal brass is "flattened" and the CCI looks "normal". For argument sake let us also assume that the composition inside is the same and the same powder etc. are the same to remove these variables.

The Federal brass by being more flattened will have been deformed more and could test as similar to or harder than the CCI brass. One would then assume it is the thickness that is the culprit. But you still don't know for sure if the difference in alloys used work hardens similarly or differently.

To test properly you need to know a few things. First what alloys are used. You would also need to know original thickness of the sheet that the cups get made from (work hardening step number one is forming the cup) and if they anneal the material before or after punching the disks that the primer cups are formed from if at all. Then you need to know the final thickness of the cups after forming (if the disks are of differing diameters to begin with, to get a final cup thickness will be different even if the original stock was the same thickness). Then we need to test fire and record the pressure differences due to primer compound composition to see if there is enough difference to matter. This is not a complete list; it is just to highlight that simply using spent primers does not at all paint a good picture on why one primer type seems softer that another.

And in my experience Federal primers show do show pressure signs way before CCI, Remington, and Winchester.

[F. Guffey]

“I remember Lee being jumped on for being bias against Federal primers...even after he explained it was not bias, but a safety issue”

It is not necessary or required for me to rely on memory, I read R. Lee's book on modern reloading, in his book he wrote he did not test Federal primers because Federal did not donate primers to be tested. If it was not for Federal primers I would be in desperate for primers. I know, if it was not for those large Federal boxes I would have more room, In my opinion Federal went to the large boxes to give R. Lee something to complain about, seems Lee customers could not figure a way to move the primers from the large tray to the small Lee flip tray, when loading primer tubes I use the large Dillon flip tray. 300 or more at a time, I am thankful Mr. Lee was not there, he would have passed out.

F. Guffey

[mehavey]

Federals are GREAT.... For everything but free-floating auto's (gas guns and Garand Actions in particular)

I generally use CCI L/S R/P & BR's as my default except. . .

- Revolvers other than the 500S&W
- BPCR's loaded w/ (what else?) BP

...where I use Federals for any number of good & sufficient reasons.




~~~~~~~~
I now return control of my apostrophes to the standards of my 5th grade teacher and the Chicago Style Manual

[F. Guffey]

Then there is the cycle of questions, if I had an interest in senility of a primer I would remove the anvil (carefully), I would then seat the primers in cases for testing. without the bang there would only be a dent, after creating all the dents in various primers I would compare dents. For bullets casters that should not be a problem, testing lead for hardness is an acquired skill necessary to be a lead bullet caster, when testing lead for hardness it is about weight, time and area.

I do have rifles with firing pins that crush primers, when I pull the trigger without a case in the chamber the fall of the firing pin goes “CLICK!”, then there are others that are more bashful.

Then there is the weight distance and speed test, again I have little interest in determining the senility of a primer, for what purpose? Pressure testing?? It has been suggested the primer is not a good indicator if pressure. I agree, I had rather use the flash hole diameter, then there are other indicators, I bundled up a small pile of equipment to assist in forming cases for a few wildcats being built, I was asked to bring ‘the other shell holder’ for magnum belted cases. We formed 300 H&H, 8mm Remington Mag, 300 Weatherby, and 300 Win mag cases to Wildcat configuration. There were 16 Browning 300 Win Mags cases that would not fit the shell holder, there were 12 Weatherby 300 Weatherby cases that would not fit the shell holder, so? I ask for the adjuster for cases that would not fit the shell holder, I ask for the small ball peen hammer, with light taps we drove the cases into the shell holder, after forming I suggested we not use the cases with the upset heads because only pressure could have crushed the case heads enough to prevent the cases from installing into the shell holder.

Then we measured the bottom diameter of the extractor grove, the groove was .007” larger in diameter than the diameter of the grooves that fit the shell holder, we also measured the diameter of the case in front of the belt, all the cases that would not fit the shell holder were .005” larger in diameter that cases that would fit the shell holder, I know, there is a collet die for reducing the diameter of the case head in front of the belt, there are just so many warnings signs I can afford to disregard, the cases that would not fit the shell holder had been abused.

There are shell holders that are more effective meaning they fit better/tighter than the RCBS shell holder.

F. Guffey