Weird primer dimples.

[Black Jaque Janaviac]

I've got a weird primer dimple. As I was working up towards max load with my 9mm I got these primer dimples that have a halo around the dimple. And if you look closely it looks like the brass flowed into the firing pin channel then got sheared.

Anyway there doesn't appear to be any signs of excess pressure other than maybe this. And the velocities seemed to gradually climb up without getting any strangely high velocities. Average velocities climbed 901 - 949 - 996, like that.

So are the dents on the left a sign of excess pressure? The cases on the right were from the lower end of the load work-up.

DSC02397 by frozenfrizzen, on Flickr

[Plate plinker]

Curious about what your load recipe. What boolit? What charge?

[Omega]

I would say that is the first sign of excess pressure, seems the primer was pushed out against the firing pin and firing pin hole.

[billyb]

I see a lot of factory ammo shot in our indoor range that will show what you are asking about. Some firing pin channels are on the large side and allow the primer brass to flow around the firing pin. I run our club's indoor range on Saturdays and see a lot of odd stuff! My S&W M&P will have primer flow and I do not hot dog any of my reloads. I do not believe that you have a pressure indicator if you are under max for what you are using.

[Tom W.]

The primers aren't flattened... did you change brands of primers?

[Black Jaque Janaviac]

Primers on both the left & right are Remington 1 1/2 - so they're the same primers.

Charge in the right-hand cases was 4.0 gr CFE-Pistol. Charge in the left-hand cases was 5.0 gr CFE. There were two more increments between the two charges that were not included in the photo. The 4.5 gr and 4.7 gr charge had primers that looked like the ones on the right. All cases exhibited soot on the outside of the case except the 5.0 grain charge.

The boolit was from Lee 358-125-2r mold using COWW powder coated with Harbor Freight Red. OAL was 1.120".

Avg velocities were:
4.5 gr : 901 fps
4.7 gr : 949 fps
5.0 gr : 996 fps

3.15" barrel length.

[35remington]

A great big pressure indicator is the velocities you are obtaining which are no greater than standard velocities even from your short barrel.

So ask yourself.....is that to be ignored?

The answer to your problem is the Remington 1 1/2 primer, which has a soft cup and flows more readily than other primers. What you are seeing is not high pressure. It is a soft primer.

When diagnosing a problem, pay attention to all the information to get the correct diagnosis. What helped is that you chronoed the velocity. My suggestion is to keep doing that when working up loads or I would not have been able to diagnose your problem so readily. Identifying the primer used confirmed my findings.

[lefty o]

lets just ask the million dollar question, does it do the same with factory ammo?

[35remington]

The Remington 1 1/2 is not a suitable 9mm primer for anything but mild loads.

Switch primers and try again.

[Black Jaque Janaviac]

Lefty,
No. I have not seen this with factory ammo. Rather the factory ammo primers seem to flatten out at the primer's shoulder a tad more.

35Rem,
I know that velocity data is valuable. That's why I posted it. I just don't have the knowledge/experience base to know how to discern a situation when there is conflicting data such as normal velocity but cratered primer dimples. I really appreciate your thoughts and expertise. I will certainly try a different primer.

I have some CCI 500s laying about the house. Of the primer brands out there, which have the strongest/thickest cups? I can go buy some.

I will also try to post some photos of the firing pin channel/firing pin to see if there is a big gap.

[35remington]

Any other small nonmagnum pistol type other than the 1 1/2 will be fine. The 9mm does not need extra thickness or hardness, just not softer than standard.

[Dan Cash]

Funny, I use Remingtons almost exclusively and the loads are full bore in .32-20, .40 S&W and .357. Colt, SIG and S&W hand guns don't exhibit this phenomenon. Funny that all this diagnostic work is done without the OP stating what firearm is used with this ammo.

[35remington]

It is a simple fact that the 1 1/2 will pierce with loads that work fine with other small pistol primers in several cartridges that I have used it in, such as the 25-20 and 22 Hornet. Stiff loads in these approximate higher 9mm pressures. The piercing is due to a combination of small firing pin diameter and high pressure.

That you have no issues does not change the fact that the 1 1/2 is a soft primer. This is quite well known here and elsewhere. If your loads are not especially stiff you will have no problems. It is most assuredly not a good choice for full power, full pressure 357 and 40 loads.

Do a search here and elsewhere. By all means do not take my word for it. 38 Special Plus P is as high as I go with them. This is also considerable experience talking when I so state what I use them for and what I do not. Mild to moderate loads, sure. 30K plus psi......no.

The loads the OP pictured are not a huge concern, but at some point the plating may build up in the firing pin orifice. To avoid it entirely, switch primers.

Easy fix. What happens in his gun is most relevant.

[35remington]

http://mp-pistol.com/mp-reloading/21...l-primers.html

Read the comments in the first post. He quotes what is printed on the box of primers. As I said, what the OP is experiencing is not a huge problem, but the primer’s softness is a known fact.

[Char-Gar]

I have seen lots and lots of those primer dimples over the years in both rifles and handguns. The primer material is trying to flow around the firing pin into the hole. Absent any other signs of pressure, those should not be a concern.

[AZ Pete]

I have had similar results from reduced power hammer springs, with both CCI and Winchester small pistol primers. I was getting consistent ignition, but the firing pin dimples were as you picture, or in some cases completely filled in. Went to a heavier hammer spring, the problem went away.


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[35remington]

I will observe the OP mentioned not seeing it with other primers.

[charlie b]

FWIW, I have used rem 1 1/2 primers for my pistol loads for decades, including hot .357mag loads. They have never failed on me.

Cratered primers are frequently the result of firing pin fit to the firing pin hole issues, not primer issues

If I see a primer issue I compare it to factory ammo before I blame it on a hot load or bad components.

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[35remington]

He did. Appearance was dissimilar, which is why he asked.

Remington’s official commentary on the matter, from the forum archives:

http://castboolits.gunloads.com/arch.../t-104552.html

[35remington]

One of the things that must be pointed out is that 9mm standard and Plus P pressures are pretty much the same as 357 and 40 pressures. This is certainly food for thought, and if the Remington 1 1/2is not recommended for 357 and 40, one may want to rethink use in the 9mm for hotter loading.

Just pointing out practical realities, from a guy who has driven them (1 1/2s) to the point of failure and does not use them in loads that make them fail any more. I would like to think I am capable of learning from wide experience.