July 2, 2021, 06:47 PM | #1 |
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Pitting
Any suggestions on what might be causing these pits? The slide is from a Ruger SR45.
[IMG]https://thefiringline.com/forums/att...1&d=1625269518[/IMG]
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July 2, 2021, 07:00 PM | #2 |
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Shooting factory or reloaded ammo?
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July 2, 2021, 07:01 PM | #3 |
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99% reloads.
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July 2, 2021, 07:04 PM | #4 |
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Loose primer pockets, hot or too low of loads to seal the primer? Or have read using mag primers instead of standard may be the issue.
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July 2, 2021, 07:28 PM | #5 |
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Could be. The primers seated nice and tight. The load I use is 6.0 grains of IMR 7625 at 757 fts. That is 2gr. below max for a 230gr LWFN
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July 2, 2021, 08:20 PM | #6 |
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I have about two thousand rounds through this handgun and this is the first I have noticed this pitting. I agree it looks like the pits are formed by gas cutting from leaking around the primer. I would think there would be evidence on the head face. Below are a few examples.
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July 2, 2021, 09:09 PM | #7 | |
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Whatever is happening, it's not happening all the time, or with 2000 rounds, the breechface would be a real mess.
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Looking at the breechface, I would guess that it's happened less than 20 times over the lifetime of the gun. I'll bet that if you look at ALL of the empties, you will find a few that stand out.
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July 2, 2021, 09:16 PM | #8 |
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I check out my firearms very closely when cleaning. I did a thorough cleaning Wednesday night. That is how I found these pits. I am pretty sure they were not there the last time I cleaned it. The reloads I shoot through this firearm are all the same. I have been using the load data for quite a while. Only thing that varies is brass. I use S&B LPP.
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July 2, 2021, 09:36 PM | #9 |
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Thank you to all who responded. I will check back later for any new responses.
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July 2, 2021, 09:54 PM | #10 | ||
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How many rounds did you shoot your last session? Quote:
I would say that during your last shooting session, something like 10-15 rounds leaked gas around the primer. Which means that unless you shot only a very small number of rounds, probably the majority of the rounds you fired were normal.
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July 3, 2021, 11:17 AM | #11 | |
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July 3, 2021, 11:56 AM | #12 | |
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July 3, 2021, 01:31 PM | #13 | |
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I do know from experience that a pierced primer in an AR-15 can burn the tip off of the firing pin. Don't know if a loose primer pocket would create the pin point gas cutting. |
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July 3, 2021, 02:44 PM | #14 | |
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So if you count them up, and assume that the much larger pits could have been the result of two or three incidents that happened to be in more or less the same place, you end up with something between 10 and 15. It's also possible that one primer could have leaked in multiple places which would mean that it could take even fewer incidents to cause the damage, the assessment above was based on the idea that each of the problem cases only leaked in one small spot. What I was trying to get at was that looking at only 3 cases from a shooting session that presumably involved a significant number of rounds fired (more than just a few magazines full) won't really provide much information given that the number of faulty rounds was likely quite small--certainly no more than 15, and potentially a lot fewer than that.
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July 3, 2021, 02:53 PM | #15 |
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A local gun store with an indoor range ran across pitting that was rapid and constant, which turned out to be caused by the primer. As I recall, it was a Tula; may not have been, but they consistently pitted .45's, and were loaded by a commercial facility.
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July 3, 2021, 03:37 PM | #16 |
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Attaching a couple.
I was pretty lax in getting around to cleaning my guns. And, honestly, may not have been as attentive as I should have been, due to known side effects of a med* I had been on for a couple years prior. Glock looked over the slide, and recommended replacement, which I did. Springfield looked over the XDS slide, said I could replace. I didn't, haven't had any issues with the gun since. *The never to be sufficiently abhorred Lupron.
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July 3, 2021, 08:17 PM | #17 |
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Maybe I am all wet but in your magnified photos, it looks like your firing pin strikes are heavy. Not uniform round like I am used to seeing on my spent primers, Any chance your firing pin is puncturing the primer just enough that you are getting enough blowback through a punched primer to cause gas cutting?
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July 3, 2021, 10:44 PM | #18 |
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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 THR forum. Please excuse the fact that some of my replies there may mirror the ones here. Thanks to all who have responded so far.
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July 3, 2021, 10:57 PM | #19 |
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If it were my gun, I wouldn't have any problems at all shooting it in that condition.
I would (as you are doing) take steps to prevent it from happening again, but I don't think there's anything other than aesthetic damage done at this point.
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July 3, 2021, 11:09 PM | #20 |
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Thank you kindly JohnKSa . My feelings exactly.
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July 4, 2021, 12:45 AM | #21 |
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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. It pointed me in the right direction.
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July 4, 2021, 05:56 AM | #22 |
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That's actually best case given the circumstances. Now that you know exactly what caused it, you know exactly how to prevent it in the future. Pretty good news if you ask me.
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July 6, 2021, 11:56 PM | #23 |
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The reason it does not look like gas cutting to me is primer leakage gas cutting will be around the firing pin hole,where the gas is jetting past the primer.
Those "pits" are located out near the rim diameter. I cannot see any gas getting to that location still carrying the heat and pressure to cut. I don't think its gas cutting.I don't think its about the primer. The rims of those cases look torn up. The beat up rims are at the right diameter to match the dents in the breech face. You get to be the one to play detective.I don't have the gun to look at. I suppose a bit of contamination could have embedded in the brass. But there is something else. Solids are not compressible. I spent a career building and running plastic injection molds.These were mostly developmental molds. The steel was "pre-hard". It was roughly a 4140 alloy,semi-hard,but machinable with high speed. The parting line ,where the mold halves separated,would start out surface ground flat.Pristine! Beautiful!! But if flakes came off the sub gate break,or of wet material caused nozzle drool,or if for any other reason bits of nylon or Delrin or Lexan or any other plastic remained on the plates when the mold press clamped up, That plastic would be pressed into the steel and it would displace the steel. The plastic is mallable,but its not compressable. If the mold was made poorly,and ran dirty, some parting lines literally looked like they had been worked over with a hammer. That beat up brass may be impressing into the steel. The high spots focus all the force on a very small area. There is something else that could aggravate the situation.I know nothing about how Ruger makes those slides.I doubt they are machined of bar stock. Ruger has been an innovator of production methods. No one is better at investment casting. IMO.its possible that slide or breech face is a powdered metal.sintered part. Pressed and baked like a cookie.I'm not saying it is,but modern manfacturing methods are a fact. Looking at your breech,zoomed up,those are dents,not gas cuts,IMO Last edited by HiBC; July 7, 2021 at 12:09 AM. |
July 7, 2021, 12:35 AM | #24 | |
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You can also see the polish mark on the extractor where the case rims have rubbed against it. Well outside the ring of pits. The pitting is much closer to the firing pin hole than the rim of the cartridges. The pitting is right where the edges of the primer pocket would be. There's no way that the rims are denting the breechface and leaving those marks. For one thing, brass is not hard enough to dent steel. For another, if they were somehow hard enough to dent steel, they wouldn't be making little pits, they would be making rim-shaped dents. And finally, the dents would be where the edge of the rims hit against the breechface, not where the edge of the primer pockets are. The gas isn't leaking out of pierced primers, but around the edges of a primer, probably due to loose primer pockets or something similar.
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July 7, 2021, 01:17 AM | #25 |
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Given your reference to the extractor,I looked at it again.
OK. I can see my sense of scale was off. You have convinced me. I got it wrong!! It happens. With the pitting at primerpocket diameter, I agree with gas cutting/leaking around the primer. To the recycle bin with the rest!! |
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