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M&P .40 kaboom

Discussion in 'Handloading and Reloading' started by 0to60, Oct 27, 2013.

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  1. 0to60

    0to60 Member

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    Here are some pics of my buddy's SW M&P .40 after he fired what we're guessing musta been a double charge. This round was supposed to be 7.5 grains of Power Pistol under a 140 grain MBC truncated cone bullet.

    The remains of the case were very tough to get out of the chamber. We had to tap it out with a screwdriver down the muzzle. The case is an absolute mess. Notice how the rim is completely gone. The upper part of the case was forced rearward enough to completely collapse the rim. The frame has been mortally wounded, and many of the small metal parts inside have been broken or sheared off. The extractor was blown completely out, but other than that the slide seems fine, as does the barrel, chamber, ramp, magazine and shooter's hand.

    I'm thinking this was definitely a double charge. He said the flash and bang was considerably more than a normal round. He says that a double charge (15 grains of Power Pistol) very nearly fills the case, but it is possible. He reloads with a Dillon RL 550, and this DOESN'T have an auto indexing shell plate, which makes it a bit easier to make this mistake.
     

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  2. oldillini

    oldillini Member

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    Glad he is okay. Potential for serious injury. He is fortunate. Looks like a new M&P is in order though.

    I have been reloading for only a couple of weeks, but I could see how it happens, at least with my set-up. I have to be cautious and keep distraction to a minimum.
     
  3. 44vaquero

    44vaquero Member

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    More likely it was bullet set back causing a radical (IE Massive) increase in chamber pressure. 40's can be very susceptible to over pressure due to bullet set back bullet if neck tension is not correct.
    Happy that no one was injured!
     
  4. joed

    joed Member

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    My thougts too. Pretty hard to double charge 7.5 gr of Power Pistol in a case that size.
     
  5. GaryL

    GaryL Member

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    Wow! Glad he is ok, and thanks for posting that up.

    I load on a 550, and whenever possible, choose loads that nearly fill the case for that reason.
     
  6. JRWhit

    JRWhit Member

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    I can't believe his hand is o.k.
    Maybe it's the light reflection,but that slide looks bent in the pic.
     
  7. rsrocket1

    rsrocket1 Member

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    14 grains will fill the case to the rim. I don't think this was a double charge. I agree it was probably too loose a bullet fit that led to a setback. You should take the remaining bullets and see if you can push them in. If you can press them in with anything less than leaning into it with your body, they are probably too loose.
     
  8. bigfinger76

    bigfinger76 Member

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    That's why I'm not a big fan of light .40 bullets - reduced bearing surface. But I'm surprised a lead bullet would set back like that.
     
  9. CharlieDeltaJuliet

    CharlieDeltaJuliet Member

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    Just glad he is ok. Send it back to S&W. They should send a new one with the same serial.
     
  10. bigfinger76

    bigfinger76 Member

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    That's a joke, right?
     
  11. Hangingrock

    Hangingrock Member

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    :uhoh:Warranty S&W I don't think so. They'll have a problem with the use of reloaded ammunition.
     
  12. Mac45

    Mac45 Member

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    Glad your buddy is OK.
     
  13. sexybeast

    sexybeast Member

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    I think it was a double charge. My friend loaded a squib, shot it, chambered another round and shot it. Both bullets exited and the barrel bulged. But the damage was not as bad as that.
    If it was bullet setback it would not have been that damaged, especially with a 140gr lead bullet. I shoot those too, probably over 10,000 of them by now.
     
  14. 0to60

    0to60 Member

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    If the neck tension is too loose and the bullet set back, it doesn't seem like pressure could get high enough to blow out the frame. Wouldn't a loose crimp allow the bullet to start moving down the barrel sooner? I would think the path of least resistance would be to push the bullet out the barrel rather than blow out the frame.

    Now if the crimp was too TIGHT and the bullet seated too deeply, I could see the frame being the path of least resistance.

    The other thing I can't understand about the neck tension explanation is, how is this not more common? Crimping is the least scientific part of reloading. Powder gets measured, bullet seat depth is measured, but crimping seems to be "eyeballed" by a lotta reloaders. If "eyeballing" incorrectly can lead to such a catastrophic result, I'd expect to hear about this a lot more.

    Educate me!
     
  15. Conservidave

    Conservidave Member

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    Taper crimping is more of a "Feel" for me, but I load on a single stage. Case mouths can and should probably be measured for proper size. Glad your buddy is OK.
     
  16. sexybeast

    sexybeast Member

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    Well put and well said:
    Also: Its a light and lubed bullet, large bore, and also lead which accelerates easier.
    Good thing is was an M&P and not a Glock. Because then it would be the guns fault!
     
  17. 918v

    918v Member

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    I don't think it was either. A double charge would not have allowed your friend to seat a bullet. Bullet setback would not have increased pressure appreciably with his powder. This was prolly caused by a defect in the case head, such as a Crescent Mark caused by brass flowing down the feed ramp which is often ignored as long as the sizer sizes the case enough to chamber.
     
  18. readyeddy

    readyeddy Member

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    I don't know if it was a double charge, but it's not hard to compress a load with the powder close to the rim. I've heard of folks loading 30 06 by using the case as a scoop and filling it up and compressing the load.
     
  19. Steve C

    Steve C Member

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    40's have been having KB's ever since they where introduced. The cartridge is high pressure (SAAMI max is 35K psi) and the barrels are often not fully supporting. Reloading cases that have been stretched at the base from being fired in less supported barrels known to weaken brass is a hazard, one needs to examine any range pick ups well. Another problem seems to be new reloaders with progressive machines who are more interested in how fast they can produce ammo than how good their QA is. Your buddy learned an expensive lesson in that regard. Hopefully others will learn from his experience.

    The good thing is that KB's seldom result in any serious injuries and your buddy wasn't hurt.
     
  20. steve4102

    steve4102 Member

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  21. hentown

    hentown Member

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    I've loaded and fired over 300,000 rounds through my Glocks...only had one KB, and that was setback-related. The .40 is particularly susceptible to setback-induced KBs.

    This is not a .40. Was a .400 Cor-Bon. Was caused by feedramp-induced setback. Slide was ruined; however, Glock took care of me...not free, but cheap.

    Port.jpg
     
  22. CharlieDeltaJuliet

    CharlieDeltaJuliet Member

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    I never said warrantee , I said they will fix it. It will cost a pretty penny, but I bet less than buying a new gun.
     
  23. 0to60

    0to60 Member

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    How were you able to verify this?
     
  24. 918v

    918v Member

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    When Clark double compresses 14 grains of Power Pistol under 124gr bullets in 9mm cases , fires them through a semi-auto pistol, and lives to tell about it there can be no doubt this was neither bullet setback nor a double-charge. Power Pistol is pretty much stupid proof.

    I recently resized 3000 once Glock-fired .40 cases through my Redding GRX push-through carbide sizer. Understand the Glock .40 chamber is really big. Cases fired in Glock .40 chambers expand a lot. Current Glock .40 chambers are better supported than earlier ones, but they still big! So when u run one of those cases through a GRX and it's thin carbide insert, you learn a lot about the case. Imagine trying to put your wife's wedding ring on your finger. That's what's happening to a Glocked .40 case as it's being pushed through a GRX die. You get instant feedback through the handle of your press if there are any defects in the case head. I trashed about 100 cases because they felt like a ratchet, like I was swaging a screw. These cases looked normal otherwise. What do you think would have happened one two or three reloads down the road?
     
  25. sexybeast

    sexybeast Member

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    Quote from the article:
    This seems to be public perception! But no matter what the writer did he could not blow up his gun. Too many people have read that .40 cal is an evil, dangerious, explosive, and badly designed round that should never have been invented.
    I have a Gen 2 Glock 22 [pure evil]! and I load the brass over and over and I also shoot lead through it. Some here think I must have a death-wish!
    But after at least 10,000 rounds I've had no issues with it or the brass. Of course I find a split case now and then and toss it
    I've had a split/ruptured case in 9mm and 45. In the 9 in my g17 the case split/ruptured and gas blew out the mag and cause the trigger spring to disconnect [easy fix]. The bullet seemed very light as it must have bairly left the barrel and the case did not eject and had a rather small hole where the gas escaped.
    Look at the M&P 40 pics. It was a double charge that was compressed by a small 140gr lead bullet which does not go that deep into the case. I know because I load thousands of these every year.
    Send the gun back to S&W. I know Glock will [if asked] to produce another frame with the same serial #, S&W may also. But just like Glock, Springfield, and others they will probably get you going with a new gun at a reduced price.
     
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