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Bulging at base of 9x19 cases


matt2ace

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I have reloading 9mm major (9x19) for a couple of year now. I buy once fired brass and typically do not pick it up at matches. I have been reusing my own reloaded brass picked up after practice sessions. This brass has been reloaded 2-3 (maybe 4) times. I don't mixed 'pick up' brass with anything I purchase as once fired. I use 7.5gr Silhouette, WSPM, 1.16OAL , using a u-die. The load makes a 170PF with low SD even with mixed cases.

I recently started finding cases with a uniform bulge around the entire lower end of the case (see pic). These cases obviously are not usable anymore. I have never experienced an FTE, nor do I notice any difference in recoil when this bulging occurs. No signs of primer flow or any distortion in the primer. Also, there has never been a burst case or signs of cracking. I typically find a few of these cases when I pick up my brass after practice.

The only answer I can come up with is that these cases are wearing out and the bulge is a result of fatigue near the web due to multiple resizing with a U-die. I am not an expert so I thought it might be nice to get some feeback here.

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Edited by matt2ace
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Wow! The only time I've ever seen a case look like that is when I ran a .40 through a 9mm die. I've loaded 9's for my Open blaster 6 or 7 times (or more) and I've never seen that. You're SURE they're your cases???

I load 8.4 to 8.5 Silhouette under 115's for about a 173/4 PF.

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If you are positive they are your cases, then is there a chance your gun is firing slightly out of battery? You do case gauge your ammo, right? If the ammo is slightly swollen at the base, as 9mm major tends to do, & the gun is NOT completely in battery when it fires, you might could get swelling like that. That is really excessive swelling.

Be careful, eventually one of those rounds is going to let go when it fires.

Are you shooting these in the gun in your avatar?

MLM

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That's a tremendous amount of case head expansion. It means you are way over pressure on that brass.

If it only happens with one brand, stop using it, before you have a blowout. If it happens with more than one brand, stop shooting that load right now!

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The more I look at that picture the more something just doesn't look right. The rim and web are the same size. The "case" part is smaller than the rim. Something is just off. You're sure it's one of yours that you fired in your gun? It looks like it was run through the wrong sizer die. :wacko:

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Let me try to answer all of the postings above.......

I am sure these came out of my gun. I picked that specific case up off the floor of our the shoot house at my range, there were no other 9mm cases on the floor at the time. This is a very new occurance for me. I shot several thousand rounds last year without ever observing anything of this type.

Yes, the gun in the avatar is the only 9mm I had at the time.

I use a u-die and chamber check my rounds, they all go through the checker. I have considered going back to a standard sizer die.

The load I am using is very common for Silhouette through 9mm open guns. It makes 170pf and shows no signs of primer issues at all.

There is no common head-stamp on the bulged rounds.

I know of many people who reload 9mm cases many times so it really hard for me to believe that this is case wear-out.

Could this be an out-of-battery problem? I have tried everything I can, dry-firing, to get the gun to fire out-of-battery and I cannot. I am basically holding the slide slightly out of battery it won't break a shot. Is there any established method I can use to test for this problem

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Edited by matt2ace
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The more I look at that picture the more something just doesn't look right. The rim and web are the same size. The "case" part is smaller than the rim. Something is just off. You're sure it's one of yours that you fired in your gun? It looks like it was run through the wrong sizer die. :wacko:

That's what I was thinking too.....something isn't right. Excessive pressure can't make the rim diameter larger (at least not a significant amount). I'd be curious to know what the case mouth diameter is of that case as well as what the swelled part and rim diameter measure.

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QUOTE (SLM @ Mar 21 2009, 01:12 PM)

The more I look at that picture the more something just doesn't look right. The rim and web are the same size. The "case" part is smaller than the rim. Something is just off. You're sure it's one of yours that you fired in your gun? It looks like it was run through the wrong sizer die.

That's what I was thinking too.....something isn't right. Excessive pressure can't make the rim diameter larger (at least not a significant amount). I'd be curious to know what the case mouth diameter is of that case as well as what the swelled part and rim diameter measure.

I would do exactly as suggested and measure some cases, about 10 will give you enough data to form an accurate opinion. I would then size some of your cases in another brand of die or dies. The more the better. It MAY be a faulty or wrong die (which is what I am leaning towards check calingre shown on die, ensure iy does not say 380 or 38Super), it MAY be faulty brass, it MAY be a faulty load, it MAY be a faulty gun (chamber, lockup, etc). Or it MAY be any combination of any or all of the above. You have to be CERTAIN. Then and only then you are able to correct the problem.

Edited by gm iprod
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They are definitely 9mm cases.......

I will do some measuring of the case in the pic. I will also pick through some recent spent cases to see if I can find more and measure them up as well.

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OK, so I am DOPE.....a BIG friggin DOPE. I should have taken your warnings to heart. I should a listened to voice in my head telling me to diagnose the problem and/or see a gunsmith before shooting a match with it. Well, I did not......and fortunately, I was not hurt.

You all know where this is going......yes, I shot a match today with the gun and yes, a case blew out on the 5th stage . Being a lefty, it blew right in my face :surprise: . As I said, no damage done to me or the gun. I had experienced a couple of cases where the gun was not fully in battery after a shot and had to clear the round. I was not able to find those rounds until after the match. YUP.....bulged just like the posted case (all different headstamps). Then I get the blown case as you see in the pix.

Scary, more than you can imagine.

I pulled the gun apart, nothing obvious. I hope to send it back to builder, Errol Lawson, if I can get in touch with him to discuss this further. I purchased the gun new from Dean Makkos. I was Errol (aka: Keal) was the builder. The gun has about 3-4k rounds through it at this point.

I will keep you all posted....and THANKS for your advice......if only I had taken it yesterday :unsure:

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Edited by matt2ace
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Not the first time I have seen a GECO case let go like that......I actually hold AMERC in better stead than the Geco cases......glad you are ok....Sumthin aint right with the gun or the load is way to hot......Funny how the primer doesnt look bad like I have seen with other...ooopsies.....

DougC

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Not the first time I have seen a GECO case let go like that......I actually hold AMERC in better stead than the Geco cases......glad you are ok....Sumthin aint right with the gun or the load is way to hot......Funny how the primer doesnt look bad like I have seen with other...ooopsies.....

DougC

Exactly Doug :cheers:

I know these might not be the best cases, but the bulging occured with WIN, FC, and other quality cases. The load is not hot, it's typical for 9mm major using Silhouette. The primer on this and other buldged cases looks normal.

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Gun is firing out of battery!!!

Check to see if firing pin spring has broken and causing the pin not to retract. If not, then you are getting slam fires. There is no way you would be getting that king of case expansion if the whole case was supported.

Either that or something is wrong with the barrel lockup and chamber is opening to soon.

MDA

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Gun is firing out of battery!!!

Check to see if firing pin spring has broken and causing the pin not to retract. If not, then you are getting slam fires. There is no way you would be getting that king of case expansion if the whole case was supported.

Either that or something is wrong with the barrel lockup and chamber is opening to soon.

MDA

Firing pin spring had just been replaced this year and inspected a week ago. I don't think it is slam fires, I am sure that I pulled the trigger when the case burst. I am suspecting a lock-up, it makes the most sense as i think about this more. I posted a link to this thread on the gunsmith forum looking for advice on what to inspect for a lockup problem.

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have you measured the chamber of your barrel and compared your numbers with someone who has the same barrel or one thats close to what you have? for reference use only, you could use a case gauge for some generic numbers but numbers from an actual barrel would be better. measure at 3 depths. if those fired cases are from your barrel, i would start looking at the chamber of your barrel.

Edited by yoshidaex
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have you measured the chamber of your barrel and compared your numbers with someone who has the same barrel or one thats close to what you have? for reference use only, you could use a case gauge for some generic numbers but numbers from an actual barrel would be better. measure at 3 depths. if those fired cases are from your barrel, i would start looking at the chamber of your barrel.

I do not have a gauge capable of measure chamber diameter at multiple depths in the barrel. I don't think that it is a chamber issue. The bulged cases will not fully fit into the chamber and being full circumference I believe they are occuring due to an out of battery situation.

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I just discovered that the problem is the load, not the gun. My new Gan's built gun is showing the same bulging problem as Errol's gun. I had 2 loads with me. My original 7.8gr Silhouette and 7.6gr Silhouette and both are showing bulging cases. 7.6gr is making 175PF and 7.8gr is making 180PF. I also measured a bunch of cases and found that they were shorter than the OAL I had thought my press was set up for. I was getting as low as 1.15 OAL when I expected slightly over 1.16 OAL. I also realized that I am using a new can of Silhouette. All of these conditions combined could be the reason for the overpressure.

I ran close to 4000 round last year with this same load but at 1.163 OAL without any signs of bulged cases.

So, I plan to reset my press to 1.165 OAL and setup new loads starting at 6.2gr and chrono it all to see if I can find a 170PF load that is not showing signs of over-pressure. I am also going to try some HS6 to see how that will work, I just need to find a good starting point.

It's a shame that I just purchased 12lb of Silhouette. I would love to use that powder, it is very clean.....but I won't take risks with over-pressure for a $150 worth of powder.

I will post more info when I get through with my test loads.

Edited by matt2ace
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What was the ambient temp when you shot your Silhouette loads?

If i recall many members here say Silhouette is reverse temp sensitive.

That might also be contributing to your bulged case issue.

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What was the ambient temp when you shot your Silhouette loads?

If i recall many members here say Silhouette is reverse temp sensitive.

That might also be contributing to your bulged case issue.

I have not seen any temp affect with ramshot, I have shot ammo made the same day in florida sunshine and the VT winter.

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I believe that I am using an adequate crimp. I did load/unload a round and there are no difference in OAL. The short OAL was due to my 550 loader. Nothing wrong with the machine, I had just not checked it to assure I had the right OAL before starting to load. I did check about 50 rounds out of about 1500 recently reloaded (at 7.8gr) and they varied from 1.151 to 1.165. I had been boxing my ammo as a I loaded over the winter so I believe that I was shooting a batch with shorter OAL recently. I plan to measure and cull out any rounds <1.163 from my current stock and pull those bullets.

Trolling through the various postings on 9mm major, it became obvious to me that I am running a pretty low OAL for 9mm major. 1.165 seems to be the low end for most people with 1.17-1.18 being the average range for OAL. I loaded up a

batch of loads at 1.17 and 1.18 OAL (at 7.4-7.6gr) and culled a box of 7.8gr loads with OAL >1.163 from my current ammo.

Going to the range tomorrow to chrono it all through both guns. I will post the results in detail tomorrow evening.

I discussed the pressure problems with Gary Natale who built my new gun. He mentioned that the Shuemann AET barrels have a larger chamber than other mfr. Both my guns have AET barrels which got me thinking about trying a standard sizing die rather than a U-die. This would allow more case volume and less clearance with the larger AET chamber.

Edited by matt2ace
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