M&P .40 kaboom

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.

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!

44vaquero said:

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!

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

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.

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

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.

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.

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

That's a joke, right?

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

Glad your buddy is OK.

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.

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.

Well put and well said:

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.

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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!

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.

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.

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.

I don't think it was "bullet set-back".

http://dailycaller.com/2013/03/05/battered-bullets-does-bullet-setback-matter/

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.

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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.

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.

I don't think it was "bullet set-back".

http://dailycaller.com/2013/03/05/ba...etback-matter/

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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?

Quote from the article:

Armed with the common knowledge that .40 S&W cartridges are especially susceptible to pressure issues from bullet setback, and that the Glock 22 would blow up if you looked at it wrong,

Read more: http://dailycaller.com/2013/03/05/battered-bullets-does-bullet-setback-matter/#ixzz2j22NOFU2

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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.