blew up my sig...well kinda

[Jim Watson]

Do you have the case head?
Is the primer still in it?
Is the primer dented in or near the middle?

If so, you did not have the elusive "out of battery" firing.

Just because the hammer will drop with the slide back a little does not mean the gun will FIRE in that position.
Try it with a primed case if you want to know what is really going on. Wear ear muffs, a primer popping in the house is loud.

 

[ljnowell]

I'm not trying to start a flame war, but I have to say that at least half of the KBs I have seen with .40S&W and 9mm occured with tightgroup as a powder.

 

[suzukisam]

Jim- I do not have the back of the case, so I have no idea on that. I had thought about using a primed caseto do some tests. I have done this in the past, and it has worked well. I don't really think that it has an oob issues by testing, but I'll be sure tonight. However the interesting thing was that I check the magazine and it was all federal brass...how do I know what federal brass is "old". Do I assume that if I didnmt buy it new than stay away from it?

 

[GLOOB]

If it says "FC" only, it is bad. If it says "Federal" it's good. If it says "FC" and a 2 digit number, it's good military brass.

 

[Slamfire]

From what I have read, those 40 S&W's are already running hot. I suspect too much powder in a case.

in the end I spent 100.00 putting the gun back together and 5000.00 on eye surgery to remove the portion of the case that didn't stay in the gun. I've learned my lesson on safety glasses so we can leave that out of the conversation.

Yours is an excellent case would make an excellent testimonial as to why everyone should wear shooting glasses. You just don't know when something is going to go wrong, and there is nothing but air between your naked eyes when brass fragments start flying after a case ruptures.

My eyes were saved, twice, because of shooting glasses. I had two, count them, two Garands slamfire out of battery due to overly sensitive Federal primers. One blew the back of the receiver off into my face and shattered the glasses. The other, I had pit marks all over my glasses from powder and brass particles. Either event, without glasses, I would have some real vision issues right now.

I am aware of a poster who fired one of those dangerous National Ordnance A3's. The receiver was soft and the head space increased to where he had a cartridge rupture. The gentleman in issue posted that he still had brass particles in his eyes and they would get hot in sunlight, creating pain.

 

[suzukisam]

okay so an update. I checked all my brass left in the suspect magazine and it was federal, however if gloob is correct than it should be safe federal, cause it had the name not the letters. I had a smith look at the pistol today, he is not a sig smith he said it is firing well within battery. the barrel it full seated in the ejection port even though it is moving back it is not dropping yet. but I did ask him a question and he didn't know maybe one of you guys will. what should the bore diameter be on that. it's measuring .433, it feels rather large. this may be the issue, too much slop in the chamber

 

[1stmarine]

Now that I am reading through again I believe this could be due to the problem that whatnickname is referring to: Cast bullets in some autoloaders is a big NO NO. Hexagonal rifling profile with flats wider than average would create more drag/friction and could result in unsafe pressures. Even not so aggressive rifling could create this problems. It is hard to determine. So, if to this issue, you add a weaker case and maybe some other factor the CABOOM is possible under these conditions.

My recomendation is as follows:
A) Stay away from lead. This is a big warning with glocks and other pistols. hard lead alloys and good lubrication helps but the risk is there. I do not do it and I am not an expert. I only use coppers on glocks so I cannot give more advice here.

B) Find a barrel for your pistol that is safe for lead. If cost is a huge issue it would be worth to loose some accuracy but to be safe. I have seen 3rd parties offer barrels cut with different profiles that are ok for lead.

Also check the trigger and firing pin/travel. Take the gun to an expert.


ORRRR, if blowing up the gun is a concern CHECK THIS OUT! ..... http://www.thehighroad.org/showthread.php?t=567810


Cheers,
E.

 

[suzukisam]

I totally understand the risks of lead, but I just don't think that the way I shoot could possibly be a problem. I never shoot more than like 50 rounds at a time and I clean everything very thoroughly after every session. I just don't "think" leading could be the issue! I mean I usually just shoot two or three mags(12rnd) in a session

 

[1stmarine]

It has nothing to do with leading. You might shoot 2000 times w/o cleaning and not have a problem. The issue comes by the way some autoloaders hexagonal rifling works with 'soft' bullets. This is why internal ballistics is so complicated. Think of it as a bullet that suddenly puts the landing flaps down inside the barrel.
This is not a myth and it has been well documented by many experts.
Let me see if I can find an article.

 

[Jim Watson]

he said it is firing well within battery. the barrel it full seated in the ejection port even though it is moving back it is not dropping yet.

That is the design. "Firing out of battery" is kind of like "went off while I was cleaning it" or "went off when I dropped it". A simple, reasonable, logical explanation... that isn't so.

what should the bore diameter be on that. it's measuring .433

I trust you mean chamber diameter. A little more important than the usual clip vs magazine trivia.
SAAMI spec for the .40 chamber at the mouth is .4284" -0, +.004". So you are less than a thou over the maximum which I doubt is going to blow a casehead.

 

[suzukisam]

yes I did mean chamber..sorry I have a lot going on here while I'm typing. but that does seem to be sloppy then? I wonder if I should replace the barrel?

 

[GLOOB]

I wonder where you got your load data from.

Just from looking at Hodgon's site, it shows 4.7 gr TG is the max load for a Hornady XTP plated hollowpoint. I thought in general, you backed off a bit for lead loads. But I know that's not always the case.

Then, if you compare TG max velocity in the 180 grain XTP category, it's much faster than even some of the slower powders. Makes me wonder if they were a bit optimistic for that particular powder.

Fast powder, big charge, heavy bullet, lead bullet, .40 cal. That wouldn't be my first choice for a bulk plinking load.

 

[pmec]

suzukisam,
I once had a OOB situation but didn't pull the trigger. It was due to the OAL of the cartridge being too long. Are you sure that the cartridge length was short enough for the ogive of the bullet and didn't cram into the rifling? That would cause some serious pressure buildup. Just a thought

 

[1stmarine]

Ok. I went back to some books I have and read about rifling and lead.

SIG, I take the rifling is hexagonal right?
What is the twist of rate you have?
What was the grain of the bullet?
What is the speed of that load?

If do not know all these questions this is what you need to consider.

rate of twist might be too fast for a .40 caliber to start with. Not a problem with hard coppers.
If you add hexagonal rifling you might have the situation that the bullet never fully engages in the rifling leaving a deadly trail behind that will increase pressure for the next round.
If you add a higher grain bullet you add pressure.
If you add speed you add pressure.

So I am curious to the answers. The solution might be as simple as a barrel swap to shoot lead as I suggested.

Cheers,
E.

 

[Tomcat47]

Below is JPEG of .40 S&W Case! The Case Diameter Should Be .4228 (10.74mm)

I would try to find some measurements from Sig for the Barrell and see if it swelled due to a double charge?

There is a long history of case failures in .40 and some articles especially regarding reloading for this caliber, due to the dies resize to SAMMI specs which make the buldging case problems due to looser chambers and large feed ramps. (must resize smaller than factory dimension?)

I searched and searched and could not find a Chamber Dimension for the .40?? But I would feel that your measurement leaves too much clearance. I checked my 9mm and I am seeing aprox. .004-.005 clearance checking with feeler guauge..(Did not have my calipers handy)

Your numbers show a little over .010! I dont know if that is acceptable for .40
Good luck and glad all is well with eyes and all.

 

[suzukisam]

marine- I really appreciate your input and I just want to thank you for coming back, and let you know I'm really thinking through your suggestions. I'll try to answer what I know.
I haven't been able to confirm nor deny the poly/hexo/octo-gonal barrel I've tried to look it up and can't find it. but I have fired many rounds of lead, and clean thoroughly between so I would guess that even if lead was a factor it must have been amplified by another issue. just my thoughts.

My oal is good for the bullet I use. and dropping my loaded cartridges into the barrel they fall easily into the proper position. no stopping on the bullet. as far as I can tell.

as to twist I think sig says 1:16

as to speed I have not chroned it but it would be a little over 900 based on the data!

I worked up a load with hollow points and stopped at 4.5. the spread is 4.2-4.7 I stopped at 4.5 this is half the spread though the spread is a small one it showed no signs and shot very accurately. I also got confirm from others that they had good results with the same load. I then worked my lead up to this same load because the lead data wasn't as prevalent for this bullet/powder combo. and again it shot very accurate and had no pressure signs.

and just to be honest a bottle of wine after a long day has disappeared as I read and responded.. so I may have to edit tomorrow.... if I was loading I would not have drank wine so that was not the problem

 

[1stmarine]

Several things for consideration: (some you might have considered already)

LOAD
- Once fired .40 cal might have bulge. Typical bulge is .010"? You need to correct with a die dedicated for this.
- Proper length of the cases (trimming). Measure the cases not just OAL.
- Find a powder with the right density so a low charge or double charge will be obvious (visual inspection)
- Keep the speed down while we keep the desired level of powder so there is no loose powder inside (this is where powder density helps).
Also related to the point above whatnickname made (very wise advice) to avoid a detonation.
- Use harder Lead alloy. Higher % of tin? I am not an expert on this.
- Stay with average grain. Avoid too light or specially too heavy and what is right for the twist of rate and lead.
- Use the harder primers. Different makers use different thickness. A good way to potentially avoid unwanted ignitions.
- Measure the loads every 10 and also weight with a precision scale. Previously to reload sort the brass by make and nr of firings and then weight
after reloading a nr. of bullets. (lets say every 20 bullets) the total weight should indicate any anomaly like a light charge or a double charge but
this risk is already minimized by the step above where we use a different density and visual inspection to reduce this possibility. To find out a bad
bullet you do not have to weight the entire batch. you can always use a dichotomy method to get to the bad round in 3 or 4 steps.


PISTOL
- Fast twist of rate for lead. FAster than 1:16 is too much specially for a full length pistol. With lead and .40 less twist is a good idea.
- Hexagonal rifling should be avoided with lead. Most European makers have this. If you have this consider a 3rd party barrel with different rifling. They are cheap and you might use for coppers anyway.
- Preventive maintenance is paramount. Make sure that a strong spring is replaced as required. These are blow-back systems so this is a must.
It is better to work on a weak load to adjust to the force required to cycle properly than to have a slide that it is too weak to support well the case during the firing cycle.

After an event like this have the gun inspected by an expert. Good eyes are hard to get. I would not advice any other thing that I wouldn't want for myself.

EYES
- Try EyeSights eye protection, they are great.

Cheers,
E.

 

[243winxb]

40 S&W Chamber + Cartridge Drawings from SAAMI

it's measuring .433, it feels rather large. this may be the issue, too much slop in the chamber

Saami Chamber Drawing. pdf file type > .4274" +.004" for the chamber. http://www.saami.org/PubResources/CC_Drawings/Pistol/40%20SandW.pdf Other cartridges can be found here > http://www.saami.org/specifications_and_information/index.cfm?page=CC I feel you had over pressure from to much powder. This expanded the case body to grab the chamber wall more than normal. The brass stretched as the case head moved backwards to contact the bolt face. This caused a case head separation. I can only guess, as we may never know the cause.We need Clark to blow up a 40S&W, to see how the cartridge reacts to an overload. Maybe he has already??

 

[suzukisam]

well this also sounds plausible.. what I think I'm going to do is replace the barrel. I'm not going to load anymore tightgroup in .40. As for what I have already built..... guess I'll have to get out my welding helmet and some kevlar gloves... all kidding aside I've shot hundreds of rounds of this stuff, and this one cartridge has changed everything... I guess I will just shoot it. like I said It must have been something to do with the ones made on my progressive cause everything else was hand charged. anyone want to buy a slightly used lee pro 1000! I can't remember who said above, but I don't think I'm comfortable loading if I can't visually inspect the powder charge first anymore! That was how I always did 50 at a time in a load block, I'll keep my auto disk and just charge manually on my single stage. I'll also switch to a different powder that will make it much more obvious there is a problem. Or should I just switch powders and keep the press........soooo....confused.:banghead:

and thanks 243 for the specs.. sounds like I'm way out of tolerance.. I kinda figured when I could see with my naked eye that it was loose on the cartridge that maybe there was a problem. don't get me wrong it's close but just a little concerning. now that I have the numbers I know I was right in my assumption

 

[1stmarine]

suzukisam,
A hot load might not be the single cause of failure but definitely a contributing factor.
Many times things go bad due to a few things going wrong at the same time so what you have to do is to take some of the advice here, and with a careful analysis of your own circumstances and possibilities mitigate as many risks as you can. I think you can still use the progressive (maybe going slower) as soon as you can implement some type of tighter quality control process. Change the auto charger to an RCBS pro or try something else.
Just go though the entire post and you will see many things that can be easily implemented.

Good luck.
E.

 

[suzukisam]

okay so I called Sig today.They were very nice and not helpful at all! I asked for the proper chamber dimensions and they that is top secret he cannot tell me. I told him I could just mic a new barrel and know. he said it doesn't matter he could not tell me. so I asked if the refurbs have a new barrel and he said he couldn't say either way cause some do and some don't, it would have to be out of spec to be changed. so I asked him what that is and again he couldn't tell me. so I said well my chamber is .433 is taht too big, he said if it is over sammi than yes. all our chambers are sammi... but you can't tell me that I thought, he said I'm not telling you what we bore them to... so basically I got the run around. he did say he could confirm my chamber was too large. so my smith is going to get me a new barrel, he can get it a little cheaper than I can. we are going to take some measurements on the new barrel versus the old and see if anything is out of whack. if it's not I'll just install the new barrel and go with it. this is really frustrating. at least I'm getting a new 9mm next week so 'll have something new to blow up

 

[GLOOB]

I asked for the proper chamber dimensions and they that is top secret he cannot tell me. I told him I could just mic a new barrel and know. he said it doesn't matter he could not tell me.

That's funny! Good catch on the oversized chamber. If it's really out of spec, I'd think they'd replace it for free!?

 

[ljnowell]

okay so I called Sig today.They were very nice and not helpful at all! I asked for the proper chamber dimensions and they that is top secret he cannot tell me. I told him I could just mic a new barrel and know. he said it doesn't matter he could not tell me. so I asked if the refurbs have a new barrel and he said he couldn't say either way cause some do and some don't, it would have to be out of spec to be changed. so I asked him what that is and again he couldn't tell me. so I said well my chamber is .433 is taht too big, he said if it is over sammi than yes. all our chambers are sammi... but you can't tell me that I thought, he said I'm not telling you what we bore them to... so basically I got the run around. he did say he could confirm my chamber was too large. so my smith is going to get me a new barrel, he can get it a little cheaper than I can. we are going to take some measurements on the new barrel versus the old and see if anything is out of whack. if it's not I'll just install the new barrel and go with it. this is really frustrating. at least I'm getting a new 9mm next week so 'll have something new to blow up

Absolutely ridiculous. I have heard all about sig having bad customer service. I have avoided them for other reasons, but that gives me a new one.

 

[suzukisam]

I have to emphasize the gentlemant was very nice, and offered to assist me in making the ammo company pay for any damage(didn't tell him they were hand loads) he was just not able to tell me anything. he did offer to send out a replacement barrel @ %20 off...which was still over retail, not sure how that works. anyway I wouldn't say the customer service was super terrible, I just thought it was elementary to say that I couldn't have the specs on something so simple and not obviously any huge secret.

if any of you have a 226 .40 I'd love it if you'd measure the chamber diameter

 

[Jim Watson]

243winxb gave you the site for the official SAAMI specifications.
The number he cites .4274" with a +.004" tolerance is measured .200" in front of the breech. The number I provided of .4284" +.004" is what SAAMI gives for the chamber mouth.
Sorry, I do not own a .40; too many stories like yours. They all end with the ammo people blaming the gun, the gun people blaming the ammo. It is just a ragged edge product.