Battle of "The Bulge"

[RDA 226sig]

There have been a number of threads posted regarding 40 S&W brass that came apart during firing. Why 40? Are these cases overworked and are the failures due to strain hardening? Did the loader make a mistake? Maybe all of those things?

In an effort to answer these questions for myself I purchased five boxes of FACTORY ammunition and fired them through four different 40 caliber pistols; Glock 22, Springfield XDM, Sig Sauer P229, and Tuarus PT840. After collecting the brass and running it thourgh the tumbler I separated it by primer strikes and inspected each case.

Interestingly enough the XDM and Taurus were very consitant with regard to the diameter of the spent brass with the largest cases measuring .428 and most measuring .427 or less. The G22 was consistently measuring .429 or larger with the worst cases around .430 to .431. Typically my P229 produces spent brass that is in the .426 or .427 diameter but to my suprise a small percentage of rounds that were abnormally large with one of them measuring .433!

.433 will not go back into the chamber and I am pretty sure this had to be the result of residual pressure during extraction. These pistols are clean and in good working order, according to my Sig Sauer certified gunsmith. This reloader is going to be a bit more picky about the brass he reloads and is going to throw out some older cases.

 

[The Bushmaster]

I believe that you will find that most of the problems with blown .40 S&W cases is caused by pistols that have unsupported chambers or firing out of battery. This problem is with 9mmX19 cases too.

I've seen lots of cases like the ones you discribe that have been in service in my 9mmX19 handguns that have had no problems and they have bulged as much as your largest ones as far as comparible diameter increase after firing. My concern is with those that exibit a bulge in one place or a "pregnent" look near the case head. Those are the only ones I disgard...I have several cases in my collection of cleaned, but not resized 40 S&W cases that are at your largest bulged case and I have no problem resizing them and using them again as it is bulged evenly around the case.

 

[Walkalong]

My concern is with those that exibit a bulge in one place or a "pregnent" look near the case head. Those are the only ones I disgard..

Agreed. There is case expansion to fill the chamber, like in the pic, and then there is bulging, as The Bushmaster described.

 

[rdhood]

I believe that it is because we are looking at
1) cases nearly full with powder
2) typical pressures between 30,000 - 35,000 CUP
3) varying support in different guns.

A small accidental overcharge, bullet set too deep, bullet set back during chambering, soft brass, etc, can all contribute to disaster in .40 S&W.

 

[243winxb]

40 S&W Bulged Case

see blog posts here dated 4/23/09 and Update on april 28th. Great photos too. http://frankwjames.blogspot.com/search?updated-max=2009-04-26T18%3A32%3A00-07%3A00&max-results=7 April 28th here> http://frankwjames.blogspot.com/2009/04/revisiting-my-40-s-advisory.html

 

[The Bushmaster]

Holy S**t. Now THAT's bulged. That looks more like a slide unlocking too early...

 

[243winxb]

i have had 45acp's that bad, remember its only on the one side, not all the way around.

 

[RDA 226sig]

OMG!!!

Wow!! That is a true testimate to the ducility of brass. It is hard to believe that he could have brass bulge that far and not rupture.

 

[lgbloader]

Holy S**t. Now THAT's bulged.

You can say that again!!!!

LGB

 

[Walkalong]

You can say that again!!!!

And again!

 

[ReloaderFred]

Brass will take a lot of stretching, if it isn't work hardened. Most of us have found .380 cases fired in 9x19 chambers, 9x19 cases fired in .40 S&W chambers, etc. In most cases, the brass swells and partially conforms to the larger chamber, which in most cases is a large amount of stretching. Few of those stretch beyond the breaking point, unless they've been reloaded several times and have become somewhat brittle.

When a .40 S&W case is fired in a .45 acp chamber, then the case will rupture. I have one of those on my bench that I picked up at the range. It must have been exciting for the shooter, and I can only imagine his/her explanation to the firearm manufacturer as to the cause of the damage to the gun....

Hope this helps.

Fred

 

[243winxb]

Interestingly enough the XDM and Taurus were very consitant with regard to the diameter of the spent brass with the largest cases measuring .428 and most measuring .427 or less. The G22 was consistently measuring .429 or larger with the worst cases around .430 to .431. Typically my P229 produces spent brass that is in the .426 or .427 diameter but to my suprise a small percentage of rounds that were abnormally large with one of them measuring .433!

What did the web area measure before firing, if you checked it. The drawing for the 40 S&W lists it as .424" I always thought the web should never expand? http://www.stevespages.com/page8d.htm

 

[StuntHeavy]

I just started reloading .40s&w. The EGW "U" die is hard to come by these days, So I learned of quite a few people taking a Lee factory crimp die, removing the guts, and using it as a push through die. I pop a 9mm case in the shell holder to use as a ram, and pass all my .40 cases through it.

I noticed that the brass I have picked up from my buddies 2nd gen g27 passes through the die much much harder...which leads me to believe it has a larger bulge. The brass from my g23 seems to go through fairly easily.

For what its worth, I shoot a 3rd gen Glock 23 and have had no issues so far with my reloads.

 

[PecosRiverM]

And I thought this was going to be some New Reloading exercise program

Sorry I just couldn't resist

 

[depoloni]

When a .40 S&W case is fired in a .45 acp chamber, then the case will rupture.

I have several of these in my collection that didn't rupture. And it's impressive. Federals, all 3 that I have. Here's to thick-brass Federal! Looks like the bulge photos at the top just above the web but that diameter goes all the way to the mouth.

 

[SquirrelNuts]

Yowza!!!

 

[TehK1w1]

It's really amazing how far brass will stretch. This 5.56 round (center) was fired out of a 7.62X39 rifle (5.56 and 7.62X39 rounds on the left and right, respectively, for comparison).
Note that while the furthest-stretched areas ruptured (3 tears in all), the case mouth and base did not.