Flattened primers - can't figure why

[RTMiller]

I recently worked up a load for 9mm following the data on Hodgdon.com (see below). I put 4.4 grains of HP-38 under a Remington Bullet 9mm (355 Diameter) 124 Grain Full Metal Jacket (Federal No. 100 primers, COL was 1.095). After test firing at the range I noticed the primers were seriously flattened.

I thought maybe I had applied too tight a crimp so I reworked the load and reduced the crimp. The primers were still flattened when I tested the new load. Any ideas?

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Bullet Weight (Gr.) Manufacturer Powder Bullet Diam. C.O.L. Grs. Vel. (ft/s) Pressure Grs. Vel. (ft/s) Pressure
125 GR. SIE FMJ Hodgdon HP-38 .355" 1.090" 4.4 1009 24,600 CUP 4.8 1088 28,800 CUP

 

[rjrivero]

Federal primers are notoriously soft. Therefore they will exhibit signs of flattening comapred to others.

If you have access to a chronograph, then you should shoot a couple over it to see if the velocities are going to be similar to what is expected.

 

[918v]

FC-100 will flatten out at 20,000 PSI. At 33000 PSI it's gonna be really really flat.

 

[Steve C]

Primers will get a flattened appearance from both high pressure and too little pressure. Too little pressure and the case is not retained in the chamber and allowed to push back against the bolt or action face, flattening the primer.

First step is to check the charge. If you used good QA procedure during loading and checked charge throws on a scale every 10 rounds or so for weight consistency with in +/- .1 gr then you can be assured your charges remained where you had set them. If not there are numerous causes for throws to become heavier or lighter. A 4.4gr load of HP38 with a 124-125gr jacketed bullet in the 9mm is a relatively light load at start level according to all my data sources and too little pressure is more likely the cause of the flattened appearance than high pressure.

While Federal primers are often called "softer" as they ignite with lower power firing pit hits than the other brands. A better description would be they are more "sensitive" due to a different primer compound formula rather than the cup being of softer material. I have loaded and shot 10's of thousand hand loads of full power .357 magnum and 9mm ammo using Federal primers without any apparent abnormal flattening of the primer.

 

[rfwobbly]

Mr Miller -
I agree of the others assessment of your symptom. Federal primers do show pressure signs well before the other brands. I call it a "symptom" because the underlying issue seems to be that you've started in the middle of the load range with a very short OAL.

No one can simply skip the "starting load" and then be surprised or alarmed with the results. That's like tripling the recipe's chili powder.... and then being surprised when the chili is too spicy. Follow?

This is said in the most helpful and respectful way I can to simply point out that most of the safety procedures in this hobby are based on taking "baby steps" and reading (and recording in your notebook) the pressure signs as the load increases.


All the best!

 

[RTMiller]

Thanks for the replies. Here is a pic - normal and flattened.


I loaded a previous batch of 9mm using IMR PB powder (3.8gr, 32,500 psi according to the manual) and no signs of high pressure.

Interesting, I didn't know that low pressure would cause flattened primers. I had loaded and shot the HP-38 at 4.4, 4.6, and 4.8. They all had flattened primers.

 

[RTMiller]

rfwobbly quote, "No one can simply skip the "starting load" and then be surprised or alarmed with the results."

What data are you referring to? The starting load was 4.4 and that is what I started with. What are you saying I did wrong? I welcome all input. What baby steps are you recommending?

 

[CraigC]

I always defer to John Linebaugh on this issue. That in straight-walled handgun cartridges, pressure signs are extremely unreliable and cannot be counted upon as an indication of anything useful. That while one gun/load combination may show significant pressure signs at safe pressure levels, another may show zero signs up until the gun grenades. Follow and trust your load data, verify with your chronograph.

 

[Steve C]

After looking at your picture I'm even more convinced that the flattened appearance is low pressure. The carbon on the sides of the right case indicates lack of proper seal in the chamber due to low pressure, while the left case with heavier load is nice and clean. The slight pin wipe also indicates low pressure.

Hodgdon says that 4.4gr's of HP38 with a 125gr Sierra is at 24,600 CUP, the 9mm SAAMI CUP standard was 35,600 CUP (old measurement units ref. Speer 11).

 

[RTMiller]

Thanks Craig and Steve. Looks like I better buy that chronograph sooner rather than later.

 

[RTMiller]

CED Millennium 2 Chrony has been ordered.

 

[gamestalker]

What method and procedure are you using to measure your powder charge? And have you checked or trimmed your brass?
Excessive crimp effecting headspace?
And last, have you tried going a tad bit longer on the OAL?
Of most of the handgun cartridges out there, the 9mm is one of the most temparmental regarding OAL.
An example of this is revealed in a test that was performed by Speer. They deliberately seated a bullet .030" deeper than SAMMI, this resulted in a load that normally is listed as producing a 28,000 cup jumping to 62,000 cup. Though I realize this was a rather extreme manipulation of the pressures, it does support their's, and other expert's findings as to how temparmental to seating depth the 9mm can be. The reason the 9mm is so pressure sensitive lies primarily on the small case capacity. Another issue that has been identified, and for the most part has been addressed in most modern cases for this cartridge, is inconsistent neck tension. Bulets have been known to be seated deeper in the mouth during operation of the firearm, thus creating undeaired pressure increases. But based on your post stating that you are placing a crimp on your loads pretty much eliminates this scenario as a culprit. But in the same regard I am wondering, if in fact crimping the mouth, or possibly too much crimp, may be the problem. Since the 9mm headspaceson on the mouth, a crimp that changes the point of contact on the mouth could easily change headspace, and will likely cause higher pressures.
I certain that if you eliminate all of the variables as follows, primer being used, reconfirm your powder charge, brass measurements, and of course OAL you''ll be very effective in diagnosing the culprit. It's pretty evident that you already have a good handle on reloading simply because you were watching for pressures signs, good job!

 

[243winxb]

How much the web area expands would tell you if you have high pressure. Someone on this forum posted there findings. Forget who. Could not find the one i wanted. But this is interesting. http://www.thehighroad.org/showthread.php?p=5986403 SAAMI drawing of chamber and cartridge here. http://www.saami.org/specifications_and_information/index.cfm?page=CC

 

[Mal H]

I tend to agree with Steve C's analysis - too little pressure as opposed to too much. In addition to his observations, look at the firing pin indentation. It is perfectly round, meaning it didn't get much pressure on it to flatten the center just a tad. Whereas, the "normal" looking primer has a slight floor to the FP indentation.

 

[RTMiller]

Wow. Thanks for all the constructive input. I knew I would get some answers here.

What method and procedure are you using to measure your powder charge?

I was working up a load. I actually measure the powder for each charge individually on the scale and then funnel it into the primed cartridge.

And have you checked or trimmed your brass?

Checked? Yes sort of. I hand sort my brass by headstamp.
Trimmed? No.

Excessive crimp effecting headspace?

No. COL was 1.095 for both batches.

And last, have you tried going a tad bit longer on the OAL?

Not really. I was .005 longer but that was not intentional. I found it hard to fine tune to 1.090 and was settling for a little longer length figuring I would rather be safe. (The OAL that snuggles right up close to the rifling on my Sig P229 is about 1.135 so the goal is to develop a load in that neighborhood).

Since the 9mm headspaces on on the mouth, a crimp that changes the point of contact on the mouth could easily change headspace

I did check for this by dropping a round in the barrel. It looked OK to me.

I tend to agree with Steve C's analysis - too little pressure as opposed to too much. In addition to his observations, look at the firing pin indentation. It is perfectly round, meaning it didn't get much pressure on it to flatten the center just a tad. Whereas, the "normal" looking primer has a slight floor to the FP indentation.

Very observant and very interesting. I can see the difference in my picture. But I can't wrap my head around this. Do you have any links or other info about this? I am intrigued.


Thanks again for for all the awesome input. I will post back here with the results of the chrony when I get it and learn how to use it.

 

[gamestalker]

The possible with headspace is not relevent to COL, COAL, OAL these abbreviations refer to the cartridge over all length. What I was actually refering to is, how your crimp can change the headspace by allowing excessive headspace to be created with cartridges that headspace on the mouth. A crimp that effects headspace will simulates a simular effect as trimmimg the brass too much, except case capacity remians the same. Kind of follow me here?
OK, now if you have a dial caliper measure your brass, just the brass and make sure it is between the min. and max. of what SAMMI recomends.
I glanced at the pics and in my opinion, that primer looks like high pressures flattened it. Notice how it fills the entire pocket? Again in my opinion, based on almost 30 yrs. of hand loading, an excessively low pressure load will produce flat around the FP strike, but certainly not fill the pocket. Another sign of excessive low pressure is likely some heavy sooting, in my opinion. I just loaded some 124s and despite my experience, I accidentally dropped a charge that was 1.1 grains heavy. Pressures were quite high and my primers all looked exactly like that one you have shown.
+1 for weighing your powder charges! I'm occasionally ribbed for it, but I weigh every single load regardless of what I'm loading. It doesn't eliminate pilot error as I mentioned above, but it does assure an accurate powder charge.

 

[1SOW]

Mr. Miller: That IS a short OAL for that bullet.
Run a few out to 1.125" and the primers won't be flattened. I'll bet your speed at 1.125 will be between 1065 - 1075.

 

[918v]

Try a different primer. I betcha a CCI will look perfectly round.

 

[P-32]

Try a different primer. I betcha a CCI will look perfectly round.

If the flat primer was a CCI there would be a problem.

 

[GLOOB]

Did you notice an unexpected amount of recoil and/or distance of ejected brass?

With a faster powder like that, I wouldn't be surprised if the short OAL is spiking your pressures.

But just in case, I would check my scale. Weighing individual charges works ok.... if your scale is calibrated. I would zero it, weigh out ten charges, then put those charges back on the scale to see if they jive to 44 grains.

 

[RTMiller]

Did you notice an unexpected amount of recoil and/or distance of ejected brass?

It was not drastically different. Maybe just a tad snappier.

 

[BADUNAME37]

The more I shoot and develop my loads, the more I am glad I purchased a Chrongraph several years ago! Not having the speed of the bullets is like driving at night with your darkest sunglasses on!

You can easily see if your speeds are on average with published data, way over, way under, etc! Not only that, it also makes working up the trajectory at long distances much easier!

For how inexpensive they are -- $100 or less for a good one -- there is simply NO reason to be without one in today's day and age!

 

[Cherokee]

Your load should be fine, I've used that load (or more) with good results. I always use CCI primers. After you test the velocity, you should have a better feel about the load.

 

[rfwobbly]

rfwobbly: "No one can simply skip the "starting load" and then be surprised or alarmed with the results."

RTMiller: What data are you referring to? The starting load was 4.4 and that is what I started with. What are you saying I did wrong? I welcome all input.

The loads I'm looking at use an OAL of 1.140 to 1.160" with powder weights from ~3.9 to ~4.8gr for HP38/W231 with 125gr jacketed rounds. The load I shoot in competition with this same powder and bullet is 4.3gr at 1.140", which is why I commented.

I see now that you have indeed followed the Hodgdon web site, but I am lost for an explanation of how I get middle-of-the-road power from less powder with a much longer OAL. Those 2 dimensions working together should knock my pressure way down if I'm wrong, or yours way up if Hodgdon is wrong.


I'll respond again tonight when I can get to a printed manual.

All the best.

 

[RTMiller]

1SOW quote - "That IS a short OAL for that bullet.
Run a few out to 1.125" and the primers won't be flattened. I'll bet your speed at 1.125 will be between 1065 - 1075."

rfwobbly quote - "The loads I'm looking at use an OAL of 1.140 to 1.160" with powder weights from ~3.9 to ~4.8gr for HP38/W231 with 125gr jacketed rounds. The load I shoot in competition with this same powder and bullet is 4.3gr at 1.140"

Yeah. 1.090" seems too short. I'm going to try a longer OAL and test it.

rfwobbly - what kind of fps do you get with 4.3 and 1.140"?