Bulging at base of 9x19 cases

[matt2ace]

Back from the range.....with less than good news.

My Commander lenght Keal gun was 5-10pt lower PF than the full length Gan's gun.

The Keal is an AET TRIBRID II with additional small 'jet ports', the Gans is an AET 5-inch with standard 3-port comp.

The Gans gun showed signs of overpressure on all Silhouette loads and OALs. Some were minor signs, but over-pressure none the less.

The KEAL gun showed no sign of over-pressure even with my normal load 7.8gr, 1.165OAL (166PF).

This confirms to me that the over-pressure situation I observed with the KEAL gun was due to shorter than expected OAL (1.50-.155).

GECO headstamp cases are pretty weak. There were signs of over-pressure on these cases even when every other case in the group looked perfect. Even at 158PF, I found one of these cases bulged. This was the headstamp that burst on Sunday.

Summary of the chrono data (10 round for each lot in 2 strings averaged)

Powder = Silhouette, Primer = WSPM, 124gr MGD CMJ, mixed cases, U-die sized

7.2gr / 1.172 OAL

GANS Avg 1332, ES 35, SD 43, PF 165

KEAL Avg 1274, ES 26, SD 12.5, PF 157

7.4gr / 1.172 OAL

GANS Avg 1331, ES 19, SD 7 PF 165

KEAL Avg 1292, ES 38, SD 16.5 PF 160

7.4gr / 1.18 OAL

GANS Avg 1340, ES 14, SD 6 PF 166

KEAL Avg 1257, ES 40, SD 17 PF 155

7.6gr / 1.172 OAL

GANS Avg 1384, ES 33, SD 15 PF 171

KEAL Avg 1284, ES 28, SD 11 PF 159

7.6gr / 1.18 OAL

GANS Avg 1368, ES 24, SD 8 PF 170

KEAL Avg 1285, ES 37, SD 14 PF 159

7.8gr / 1.165 OAL

GANS Avg 1403, ES 21, SD7.5 PF 174

KEAL Avg 1336, ES 29, SD 12 PF 166

My next step is to try 1.19 OAL with Silhouette and replace the U-die with a standard sizer.

The increase case volume without the U-die and the longer OAL may alleviate the pressure problems with the GANs gun.

AET barrels have pretty large chambers which I suspect contribute to this problem, a standard sizer might help.

Finally, I plan to try some HS6 loads since I just happen to have 1lb of this powder.

[Glockcomma]

Your load sounds fine to me, I use 7.4 gr.'s of Silhouette, 1.155 o.a.l., .374 crimp, Montana Gold 124 c.m.j.'s any brass I can find. No signs of primer flow with Winchester or Wolf small pistol primers. I use a u die in the last position of my 650. I wouldn't be shooting a gun that was ejecting anything as ugly as whats coming out of yours, I guess now you won't be either. I think one way or another your gun is shooting out of battery, keep us posted.

[JThompson]

Matt,

I use 8.3 in mine and I don't see anything like that... I DO NOT think it's the load. I'll buy the Sil off you if you find I'm wrong. I like to load 1.165/70 but have had some short loads and no issues like that. I think that thing is firing out of battery.

JT

Edited March 26, 2009 by JThompson

[AWLAZS]

Matt,

I use 8.3 in mine and I don't see anything like that... I DO NOT think it's the load. I'll buy the Sil off you if you find I'm wrong. I like to load 1.165/70 but have had some short loads and no issues like that. I think that thing is firing out of battery.

JT

The Gans gun showed signs of overpressure on all Silhouette loads and OALs. Some were minor signs, but over-pressure none the less.

The KEAL gun showed no sign of over-pressure even with my normal load 7.8gr, 1.165OAL (166PF).

This confirms to me that the over-pressure situation I observed with the KEAL gun was due to shorter than expected OAL (1.50-.155).

Its two different guns. One is brand new.

Edited March 26, 2009 by AWLAZS

[matt2ace]

This is definitely not an out of battery problem. The same pressure issues occur with both KEAL and Gans guns, built totally different from each other. I reinspected the cases under from yesterday (better light and magnification) and found that there were bulged cases from the KEAL gun at 7.6gr and 7.8gr, it was just not obvious when I looked them over at the range.

I had a discussion with a friend who is a commercial reloader (thanks Tim!). He pointed out that WSPM primers are known to produce ~5000psi higher pressures than any other standard or magnum primer. The are acutally listed as 'special purpose only'. I had these primers because it was all I could get at one point and they worked great for my 40 loads. Tim strongly suspects that it is the WSPM primers that are driving the over-pressure condition.

You can see from the chrono data (BTW- using a Chronoy F1, suspect it is reading a bit low) that 7.4-7.6 makes major in the Gan's gun. I have 15K of wolf magnum primers and 1000 small rifle primers. Tim was clear that wolf magnum won't produce the higher pressure like WSPM. Loading them up tonight with 7.4 and 7.6gr at 1.18 OAL. I am pretty confident that is going to fix the problem.

The KEAL gun is probably going up for sale. I love the gun, built great. It shoots great too, works every time. However it won't make major with the same load as the Gans gun. I don't want to run hotter loads in the Gans gun just to make major in what will end up being my backup gun. I could use it for steel, but I really need a backup for the Gans gun if I plan to shoot Nationals and several other big matches this year. I need to finance another Gans built gun so the KEAL is probably going up for sale.

I will post more once I get the next pass of loads through the gun.

Edited March 26, 2009 by matt2ace

[JThompson]

Hmmm. Maybe someone can explain to me how you get a bulge like that in a supported chamber? Unless that powder is still igniting while that gun is unlocking and coming out of battery... there's no way it can bulge because the chamber would prevent it.

Smiths?

JT

[G-ManBart]

Hmmm. Maybe someone can explain to me how you get a bulge like that in a supported chamber? Unless that powder is still igniting while that gun is unlocking and coming out of battery... there's no way it can bulge because the chamber would prevent it.

Smiths?

JT

JT, I didn't go back and look, but I started to type something like that earlier. If the case is completely chambered and you get a crazy overpressure load, it's not going to make a circular "spare tire" bulge around the case like that. One side is going to look normal because it's up against the top of the chamber and the opposite site is going to have a bulge/blowout just barely forward of the extractor groove where the feed ramp is on the barrel.

I guess if there was some weird timing issue going on the case could be extracting while the powder is still burning and as it becomes unsupported it would bulge but that seem a little out there.

[JThompson]

Hmmm. Maybe someone can explain to me how you get a bulge like that in a supported chamber? Unless that powder is still igniting while that gun is unlocking and coming out of battery... there's no way it can bulge because the chamber would prevent it.

Smiths?

JT

JT, I didn't go back and look, but I started to type something like that earlier. If the case is completely chambered and you get a crazy overpressure load, it's not going to make a circular "spare tire" bulge around the case like that. One side is going to look normal because it's up against the top of the chamber and the opposite site is going to have a bulge/blowout just barely forward of the extractor groove where the feed ramp is on the barrel.

I guess if there was some weird timing issue going on the case could be extracting while the powder is still burning and as it becomes unsupported it would bulge but that seem a little out there.

Someone PMed me to say that the barrel used are not supported. Now that makes sense... from what we see and overpressure.

JT

Edited March 26, 2009 by JThompson

[Mark K]

I am certainly no reloading or gunsmithing expert, but I did stay at a Holiday Inn Express last night.

If you suspect that such a relatively small difference in OAL is adding to the over pressure problem, Keeping the U-Die is even more important. The smaller diameter after sizing results in a slight hour glass shape after loading - but it physically makes it nearly impossible for the bullet to be set back in transportation or by recoil.

As to it reducing case volume = the millisecond that the powder ignites the case expands to the diameter of the chamber minus case wall thickness. So at ignition U-died or not you have the same case volume.

Just my two cents worth (and with inflation you know what that is worth)

Mark

[G-ManBart]

Hmmm. Maybe someone can explain to me how you get a bulge like that in a supported chamber? Unless that powder is still igniting while that gun is unlocking and coming out of battery... there's no way it can bulge because the chamber would prevent it.

Smiths?

JT

JT, I didn't go back and look, but I started to type something like that earlier. If the case is completely chambered and you get a crazy overpressure load, it's not going to make a circular "spare tire" bulge around the case like that. One side is going to look normal because it's up against the top of the chamber and the opposite site is going to have a bulge/blowout just barely forward of the extractor groove where the feed ramp is on the barrel.

I guess if there was some weird timing issue going on the case could be extracting while the powder is still burning and as it becomes unsupported it would bulge but that seem a little out there.

Someone PMed me to say that the barrel used are not supported. Now that makes sense... from what we see and overpressure.

JT

The barrels are Schuemann AET's.....which means they're fully supported. I don't know who said that the AET chamber was "bigger" but they're not. They have a longer, different leade style and the chambers are fluted, but not larger in diameter. Brass coming out of my KKM and my Schuemann AET give nearly identical measurments. Even an old fashioned non-ramp unsupported barrel still couldn't put a circular bulge all the way around the case in the web area if the round is completely chamberd. The barrel hood covers and supports the case all the way back to the rim on the top third or so....so that part can't bulge out like a donut. R,

[G-ManBart]

As to it reducing case volume = the millisecond that the powder ignites the case expands to the diameter of the chamber minus case wall thickness. So at ignition U-died or not you have the same case volume.

I have loaded ammo in one run using the U-die for half and a Dillon sizing die for the other half. Chronograph results were absolutely identical.

Resizing a case and extra .001" isn't going to change the capacity significantly.

[matt2ace]

I get the same bulge from 2 different versions of the AET barrel (Tribrid II and Standard 5-inch) built by 2 different smiths (KEAL and Gans) with very different configurations over a year apart (Gans gun is new). There is no way that both guns have a timing/lockup problem that manifests exactly the same way.

This has got to be a problem with my loads. Once I get a chance to run SRP and Wolf SPM primers I will let everyone know how the cases look. Explaining how a full circumference bulge occurs with over-pressure ammo will probably keep this thread alive for sometime.

Edited March 26, 2009 by matt2ace

[HoMiE]

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 had the same thing happen trying to see how many times I could reuse my brass.

http://www.brianenos.com/forums/index.php?...st&p=751217

Needless to say, I don't try and reload it more than once anymore, shooting major anyways. I do pick it up and save it for minor practice ammo.

[Glockcomma]

That's interesting about WSPM primers, but like others have stated the case can't expand to that degree while in the chamber. What else might you have changed? Are you using the same lot of bullets that you were using before you had any problems? Have you measured them to make sure they are .355?

Edited March 27, 2009 by Glockcomma

[matt2ace]

There has been all sorts of debate about how these cases could bulge without the gun coming out of battery. I pulled apart both guns and took a couple of buldged cases and slide them into the chamber. They go in completely....yes, the fit is tight, but I did not have to push hard and could pull them out easily. I took some pix of the cases in/out of the barrels just to illustrate.

This leads me to believe that it is completely possible for this problem to be over-pressure in the cases and not an out of battery situation. If the cases were bulging out due to out of battery situation, I would expect them to expand even more and not fit into the chamber at all, atleast some of the cases would not fit. I tried about 20 bulged cases and every one of them fit back into the chamber as illustrated in the pictures.

The first 3 pix are a case fit into both barrels. The last 2 are a GECO (worst headstamp for bulging) in the KEAL gun barrel.

Notice how the bulge in the first case is flattend on the sides. I think this is a result of the case expanding (bulging) in the chamber and flattening on to the walls before being extracted. This flattening in the bulge is what most of the cases look like (except GECO headstamp).

Edited March 27, 2009 by matt2ace

[olp73]

There has been all sorts of debate about how these cases could bulge without the gun coming out of battery. I pulled apart both guns and took a couple of buldged cases and slide them into the chamber. They go in completely....yes, the fit is tight, but I did not have to push hard and could pull them out easily. I took some pix of the cases in/out of the barrels just to illustrate.

This leads me to believe that it is completely possible for this problem to be over-pressure in the cases and not an out of battery situation.

The first 3 pix are a case fit into both barrels. The last 2 are a GECO (worst headstamp for bulging) in the KEAL gun barrel.

I have never own a 1911 design in 9mm, but it seems to me that the camber is extremely short. I have a 9major EEA/Tanfoglio, if I take a spent case and put it in to the camber like in the pictures the hole case is supported even past the extractor notch.

Is this how it is supposed to be in 1911?

[matt2ace]

These cases are bulged as the pictures show. I did not try to push them in farther, I was only trying to illustrate that the cases could bulge out while in the chamber. I normal case does go farther into the chamber as do loaded rounds.

There has been all sorts of debate about how these cases could bulge without the gun coming out of battery. I pulled apart both guns and took a couple of buldged cases and slide them into the chamber. They go in completely....yes, the fit is tight, but I did not have to push hard and could pull them out easily. I took some pix of the cases in/out of the barrels just to illustrate.

This leads me to believe that it is completely possible for this problem to be over-pressure in the cases and not an out of battery situation.

The first 3 pix are a case fit into both barrels. The last 2 are a GECO (worst headstamp for bulging) in the KEAL gun barrel.

I have never own a 1911 design in 9mm, but it seems to me that the camber is extremely short. I have a 9major EEA/Tanfoglio, if I take a spent case and put it in to the camber like in the pictures the hole case is supported even past the extractor notch.

Is this how it is supposed to be in 1911?

[olp73]

These cases are bulged as the pictures show. I did not try to push them in farther, I was only trying to illustrate that the cases could bulge out while in the chamber. I normal case does go farther into the chamber as do loaded rounds.

There has been all sorts of debate about how these cases could bulge without the gun coming out of battery. I pulled apart both guns and took a couple of buldged cases and slide them into the chamber. They go in completely....yes, the fit is tight, but I did not have to push hard and could pull them out easily. I took some pix of the cases in/out of the barrels just to illustrate.

This leads me to believe that it is completely possible for this problem to be over-pressure in the cases and not an out of battery situation.

The first 3 pix are a case fit into both barrels. The last 2 are a GECO (worst headstamp for bulging) in the KEAL gun barrel.

I have never own a 1911 design in 9mm, but it seems to me that the camber is extremely short. I have a 9major EEA/Tanfoglio, if I take a spent case and put it in to the camber like in the pictures the hole case is supported even past the extractor notch.

Is this how it is supposed to be in 1911?

Ok, that helps. But anyway, if you can chamber the bulged spent case while the gun is locked(slide al the way forward) I think you have a severe headspace problem. Shouldn’t the breakface of the slide keep the case from backing out that much, Some movement is normal but……….

Chamber a sized case. Take the top off. Turn it a round. Take a screwdriver or similar and try to push the case a much as you can toward the breakface. Take a photo!!

How much is it??

Edited March 27, 2009 by olp73

[matt2ace]

I will give it try tonight......thanks for the suggestion.

Still, it is hard to believe that I have 2 guns with the same problem.

Ok, that helps. But anyway, if you can chamber the bulged spent case while the gun is locked(slide al the way forward) I think you have a severe headspace problem. Shouldn’t the breakface of the slide keep the case from backing out that much, Some movement is normal but……….

Chamber a sized case. Take the top off. Turn it a round. Take a screwdriver or similar and try to push the case a much as you can toward the breakface. Take a photo!!

How much is it??

[olp73]

I will give it try tonight......thanks for the suggestion.

Still, it is hard to believe that I have 2 guns with the same problem.

Ok, that helps. But anyway, if you can chamber the bulged spent case while the gun is locked(slide al the way forward) I think you have a severe headspace problem. Shouldn’t the breakface of the slide keep the case from backing out that much, Some movement is normal but……….

Chamber a sized case. Take the top off. Turn it a round. Take a screwdriver or similar and try to push the case a much as you can toward the breakface. Take a photo!!

How much is it??

I agree

[G-ManBart]

There has been all sorts of debate about how these cases could bulge without the gun coming out of battery. I pulled apart both guns and took a couple of buldged cases and slide them into the chamber. They go in completely....yes, the fit is tight, but I did not have to push hard and could pull them out easily. I took some pix of the cases in/out of the barrels just to illustrate.

This leads me to believe that it is completely possible for this problem to be over-pressure in the cases and not an out of battery situation. If the cases were bulging out due to out of battery situation, I would expect them to expand even more and not fit into the chamber at all, atleast some of the cases would not fit. I tried about 20 bulged cases and every one of them fit back into the chamber as illustrated in the pictures.

The first 3 pix are a case fit into both barrels. The last 2 are a GECO (worst headstamp for bulging) in the KEAL gun barrel.

Notice how the bulge in the first case is flattend on the sides. I think this is a result of the case expanding (bulging) in the chamber and flattening on to the walls before being extracted. This flattening in the bulge is what most of the cases look like (except GECO headstamp).

Those cases aren't fully chambered....they're sticking out past the hood. Remember, 9mm is a tapered case and because of that, moving the case back just a very slight amount will let them expand considerably. One, because of the taper and two, because the mouth of the chamber always has to be a bit oversized for feeding. If that's as far as they'll go in without ramming them in there....then that's pretty close to where they were when under pressure.

I'd want to try something like a buddy's ammo that you trust, or some Atlanta Arms 9 Major and see what those look like....I sure wouldn't shoot more of the current ammo though!

See, and people wonder why I stick with 38SC and just accept that I'm gonna pay a bit more for brass...and I get once-fired 9 free

[Rabe]

when the op started the thread, my first thought was that the cases looked like what I was getting when shooting warm loads in a blow back 9mm (linda carbine for the ones who were around back then).

Based on the pictures of the cases in the chamber, the last picture appears to show a bit of clearance between the case and the hood of the barrel. Is there any chance that someone modified the entrance to the chamber too much.

If you have stock 9mm barrel to compare how much clearance there is near the base when the round is chambered it may be interesting to see the difference

Edited March 27, 2009 by Rabe

[Jody Waring]

Back before I knew anything about working on my guns at all, I attempted something I still regret. I was 18 or so at the time and was setting up a 9mm barrel for my Tanfoglio open gun I was using at the time. The ramp was rough and the opening of the chamber had very sharp edges and I attempted my first gunsmithing job by polishing and smoothing out the ramp and champer opening. My intentions were good, but I ended up opening the chamber a little too much, it wasn't even real noticable by eye, and when I finally made it to the range and tried it out, I fired the first few rounds and the gun performed perfectly, then I just happened to look down and notice something strange about my brass. They bulged like the pics you posted as that portion of the barrel was not supporting the case and the barrel went in the garbage. Thank god it was minor PF ammo, hard to say what would have happened with 175PF stuff from back in the day! The strange thing about your situation is that it involves two different guns by different builders. I would try some different ammo and see what happens, that should automatically narrow it down to an ammo problem. Even some +P 9mm ammo is pretty hot and would be enough to give you an idea of what is going on. I wouldn't shoot any more of your existing ammo until I eliminated it as a variable to whats going on. Hope all pans out for you soon.

[norbs007]

I agree with G-Man, try different ammo from someone you trust and see what it does. I've had GECO brass in the mix and it doesn't bulge like that at 170pf. It looks like it chambers the round just enough to close the slide but not enough to have full support where it's bulging.

[al503]

I've had GECO brass in the mix and it doesn't bulge like that at 170pf.

I got some GECO brass in a batch a while back. Shot them 4x through a 9major gun without issue. Looked like they could take another loading or two easily but I'm happy getting 3-4 reloads out of my 9mm brass. (I was using SP2, which is much slower than Silhouette, though.)