pitting

[lckdnldd]

Any suggestions on what might be causing these pits?

 

[fxvr5]

if they weren't there before, gas leak around the primer.

 

[lckdnldd]

if they weren't there before, gas leak around the primer.

I suppose that could be. There is no visual evidence of that on the head of the case or around the primer.

 

[NIGHTLORD40K]

Yup, gas erosion.

 

[lysanderxiii]

I suppose that could be. There is no visual evidence of that on the head of the case or around the primer.

There won't be.

 

[lckdnldd]

 

[lckdnldd]

I agree. I have never ran into this before. These cases have been loaded about three times. Any suggestions ?

 

[lckdnldd]

Thank you to those who have responded. I will come back later to check for any new responses.

 

[NIGHTLORD40K]

Could be a trick of the light, but those look pierced......

If not, then either the pockets are worn oversize or the primers are a hair undersized. Maybe try a different brand of primer or at least some from a different lot?

 

[Otto]

That's called breechface erosion. Are you using Winchester primers?

 

[RainDodger]

Most erosion divots from pierced primers that I have seen have not been separated like that. They have run together more. Those look kind of "peened" but I can't think of any other cause. Very curious about what you find. A couple of years ago I had a bad batch of Winchester large rifle primers, which pierced in a Sako .243 and ruined the bolt in one afternoon of shooting. It took a while, but Winchester actually paid me for a $390 new bolt for the older Sako L579, after I sent the remaining primers back to them.... it was not easy to find that new bolt, either, which of course needed to be headspaced before use. That episode caused me to log my primers by lot number, which I had not done previously. Good luck!

 

[lckdnldd]

I checked out the suspect batch of one hundred rounds that where last fired through the firearm. I used a magnifying lens to inspect the spent primers and area around them. I also shined a flashlight up into the case mouth to look for pin holes. No pin holes and no real difference in the primers that I posted in the previous post. Then I checked the spent cases I loaded from a one hundred round batch fired before the suspect rounds. In comparison I noticed that the firing pin marks are deeper in the suspect rounds. Also the primers in the suspect rounds themselves were not as deeply seated. Thinking back (a couple of years) the only difference as far as loading between the two batches is that I did not clean the primer pockets. I used to always clean primer pockets on any round I reloaded. That may or may not be the reason for the primers not seating as deep in the suspect rounds? At this point that is the only thing I can come up with. I do believe that gas cutting is what caused the divots. I detected the damage fairly quick but the damage is done. I plan on making up a new batch of loads that will definitely have cleaned primer pockets to see if that alleviates the problem. If I do alleviate the issue what are your thoughts on the amount of damage. Replace the slide or live with it? I lean towards letting it ride for a while. Just an FYI, I asked this same question on TFL forum. Please excuse the fact that some of my replies there may mirror the ones here. Thanks to all who have responded so far.

 

[lckdnldd]

It is not easy to admit this especially to myself but in the hopes of helping someone else I am going to. I use a Lee Classic Turret Press for my handgun cartridge loading. For those who may not know it the Classic Turret Press uses two sizes of Primer Arms for seating pistol primers. Small size for small pistol primers and large for large pistol primers. Simply put after loading a batch of .357 mag loads and before loading the suspect 45 auto loads. I did not replace the small pistol primer arm with the large pistol primer arm needed for my 45 auto brass. Maybe I burned a few too many brain cells in the Seventies. Anyway I believe the problem is solved. Thanks again for the help.

 

[5-SHOTS]

Live with it. No need to replace the slide or things like that. The problem is very very small.
You can try an enamel paint (nail polish paints are fine too) to seal the area between the brass and the primer. This makes the cartridges even water resistant.

 

[edwardware]

I did not replace the small pistol primer arm with the large pistol primer arm needed for my 45 auto brass.

This is unlikely to have mattered; not impossible, but unlikely.

Slightly loose pocket/primer interference fit is the culprit, and it's not unusual. I think all my autopistols over 30yo show at least a little pitting.

 

[RainDodger]

It will have no effect on future life of the pistol in my opinion. It is minor.

 

[lckdnldd]

This is unlikely to have mattered; not impossible, but unlikely.

Slightly loose pocket/primer interference fit is the culprit, and it's not unusual. I think all my autopistols over 30yo show at least a little pitting.

The large primer arm only pushed the small pistol primer into the primer cup enough to be flush with the mouth of the cup. That leads me to believe that when the firing pin hit the primer it pushed the primer deeper into the cup. Then when the primer fired it backed up to the breech face allowing hot gases to blow around it. That may have caused the pitting/cutting into the breech face. Basically the same as a loose primer cup would.

 

[edwardware]

The large primer arm only pushed the small pistol primer. . .

You just switched which arm you were using vs your original explanation. . .

Also, the primer backs out of the pocket until stopped by the breech face every single time a cartridge is fired. It's perfectly normal, and doesn't cause leaking. The most common consequence of not seating the primer below flush is the primer failing to detonate for lack of seating the anvil into the cup against the pocket floor.

 

[Tirod]

When you fire the next batch look and see if the pitting is pressed into the case. Likely not. After that, check after 50k rounds for slide cracking near the port.

Not that rails won't gall or get peened, etc, but to put a perspective on what kills slides. It's usually high round count stress. 55K is the standard to pass NATO, and few civilian guns are shot that much, a lot of duty guns in service can go 100k.

That comes from a rental range results thread on another forum. Interesting things are discovered when you fire guns and put thousands of rounds thru them much more quickly than we do.

 

[lckdnldd]

Ok. Thank you.

 

[lckdnldd]

You just switched which arm you were using vs your original explanation. . .

LoL, you are absolutely correct edwardware, Lets see.....hmm, I guess old-timers disease is catching up with me