THM7 Posted December 24, 2009 Share Posted December 24, 2009 (edited) Hello, The other day I noticed some breech face erosion on my 2 month old open gun (9mm) with approx 2500 rnds thru it. A fellow shooter has a almost identical gun using a almost identical load with the exception of the primer and has no sign of erosion. I am using Fiocchi (sp?) small rifle primers under 8.1 grns of 3N37....MG 121 grn bullet...brass is once fired for USPSA and range fodder for practice and local steel matches. Is it possible that the cup of the Fiocchi primer is too hard to seal the pocket allowing gas to leak by?? I obviously do not want to damage the gun any further...and I tend to think it may be a primer problem....however loose primer pockets are another possiblity. Any insight would be appreciated. Edited December 24, 2009 by THM7 Link to comment Share on other sites More sharing options...
AlamoShooter Posted December 24, 2009 Share Posted December 24, 2009 The only time i had a problem was with Old CCI primers and a light load. That was with 38 super comp brass Link to comment Share on other sites More sharing options...
GrumpyOne Posted December 24, 2009 Share Posted December 24, 2009 The primer is probably too hard, letting the gas by. Do you get pressure signs using small pistol primers? I don't use your powder, so I can't help there. Link to comment Share on other sites More sharing options...
G-ManBart Posted December 24, 2009 Share Posted December 24, 2009 I don't know anything about the Fiocchi primers, but it could be a combination of them, plus unknown range brass that's causing a problem. If you're getting breachface erosion, the gas is getting past the primer one way or the other, so it's a loose pocket, an overly hard primer or both. R, Link to comment Share on other sites More sharing options...
Xfactor Posted December 24, 2009 Share Posted December 24, 2009 Is this a common issue with 3N37? I just bought 8# of it... Link to comment Share on other sites More sharing options...
TeamGE Posted December 24, 2009 Share Posted December 24, 2009 I find that major pf loads in 9x19 will swell the web of the case and primer pockets farther and faster then the small rifle primer cup can keep up, thus allowing gases to leak around the cup/primer pocket and erode the breach face. So using small pistol primers is a must to keep this from happening. Extra large chambers are worse for this problem then tighter ones. I once wiped out a breach face/slide in 500 rounds, not knowing it was happening till it was too late. Once I made the change to small pistol primers, I have never had the problem again. I beleive it is just the nature of the beast, the web of the 9x19 case is not as strong as we would like it to be, and this is also why I don't reload the case more then twice, at Major PF. Link to comment Share on other sites More sharing options...
Aircooled6racer Posted December 24, 2009 Share Posted December 24, 2009 Hello: This is good to know. I have been using small pistol primers and small magnum pistol primers, both are Winchester. I am also using 3N37 and I have not seen any signs of erosion. I clean my Open 9mm after each outing and that is one of the areas I check. Thanks, Eric Link to comment Share on other sites More sharing options...
G-ManBart Posted December 24, 2009 Share Posted December 24, 2009 Is this a common issue with 3N37? I just bought 8# of it... No, I wouldn't say it's a powder issue specific to 3N37. In fact, 3N37 is an outstanding 9 Major powder. The one thing to know is that it puts heat into the gun at a very rapid rate. You probably don't want to shoot more than 20-30 rounds in a row (imagine a long field course) without letting the gun cool a bit. If I'm doing static work I try to only keep one mag loaded at a time...the gun cools while I load another one. R, Link to comment Share on other sites More sharing options...
THM7 Posted December 24, 2009 Author Share Posted December 24, 2009 Small rifle primers may not be the way to reload major 9 after all.....unless the brass is new or once fired. Link to comment Share on other sites More sharing options...
calishootr Posted December 24, 2009 Share Posted December 24, 2009 I have loaded 38 super with 3n37 for yrs with zero problems with the powder, even changing to small pistol primers with no pressure problems ie. primer flow(once the extended firing pin was introduced that all went away) asfor major9, the pressures are scary to be sure, but i dontthink its a powder problem, kind of funny, people went to major 9 for a variety of reasons, most of what ive heard was the use of 'inexpensive brass' now we are seeing people who are using it for maybe 3 times??? then scrappin it, im gettin a lot more life out of my super brass at this point....may cost more but get more reloads out of it??? Link to comment Share on other sites More sharing options...
THM7 Posted January 1, 2010 Author Share Posted January 1, 2010 Just a update....I neglected to mention I "was" using a undersize decapping/sizing die....anyway I switched back to SPP and switched out the decap/sizing die back to Dillion and no more issues with the gas getting around the primer (even with range brass). I think it was the combination of SRP, Undersize decapping/sizing, and somewhat worn range brass....being new to "open" this was eye opener. THX Link to comment Share on other sites More sharing options...
magicald_223 Posted January 1, 2010 Share Posted January 1, 2010 I've got a Trubor with 2000 rounds through it using once fired range brass and winchester spp under HS6 and my breech doesn't show any wear. I've never used 3n37. Link to comment Share on other sites More sharing options...
ipscjoe Posted January 2, 2010 Share Posted January 2, 2010 buy some new brass......loose primer pockets are the culprit.... Link to comment Share on other sites More sharing options...
Xfactor Posted January 2, 2010 Share Posted January 2, 2010 Just a update....I neglected to mention I "was" using a undersize decapping/sizing die....anyway I switched back to SPP and switched out the decap/sizing die back to Dillion and no more issues with the gas getting around the primer (even with range brass). I think it was the combination of SRP, Undersize decapping/sizing, and somewhat worn range brass....being new to "open" this was eye opener.THX You really think the U-die was part of the issue? Link to comment Share on other sites More sharing options...
lucasb67 Posted January 2, 2010 Share Posted January 2, 2010 I agree with Xfactor, I don't understand how the resizer can influance this Link to comment Share on other sites More sharing options...
GrumpyOne Posted January 2, 2010 Share Posted January 2, 2010 Re-sizing couldn't be the culprit unless he was also swaging his primer pockets. It was his change back to small pistol primers that cured the problem. I use small pistol primers exclusively, and, while with some powders, I do see some cratering or maybe the tiniest bit of primer flow, but 99.9% of the time, the primers look pristine (well, pristine for a fired primer anyway) out of my 40, 38/357, 45 and 38 super. I understand the advantages of using the SRP's, but to me, the disadvantages outweigh the advantages. Link to comment Share on other sites More sharing options...
THM7 Posted January 3, 2010 Author Share Posted January 3, 2010 You guys are most likely right...it was recommended I use the undersized die for 9mm major. I found it to be a pain in the "a s" and did nothing for reliability. Also some of the cases would not size evenly....I do not think the lose chamber tolerance helped with the erosion problem....ie. undersized case in chamber. Link to comment Share on other sites More sharing options...
Xfactor Posted January 4, 2010 Share Posted January 4, 2010 You guys are most likely right...it was recommended I use the undersized die for 9mm major. I found it to be a pain in the "a s" and did nothing for reliability. Also some of the cases would not size evenly....I do not think the lose chamber tolerance helped with the erosion problem....ie. undersized case in chamber. Not to beat a dead horse, but... did you have erosion on the periphery of the breech face? (in a ring around where the base of the case would rest against it?) If there were back flow coming around the outside of the case, then I guess this is what you'd see... but I don't think that would happen because the case swells to the chamber dimensions upon ignition, thus sealing off any potential back flow around the outside of the case. Anyway, glad to hear that your issue is resolved. Link to comment Share on other sites More sharing options...
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