Cartridge go boom in Sig M-17

First time ive had this happen, no real clue what caused it....or more specifically alot of variables involved.

Handloads, fired brass sourced online, branding is blazer brass. Id have to ask the load, but it was mid range at best with w244. Velocity running 1100 with 115s.

Blew open at the case head rim junction (these look thinner than ive seen there), upper right side where the extractor grabs.
Only damage to the gun was the extractor got launched.

Bullet underneath was scored pretty deep, but the magazine didnt launch or even take any damage.

With the high ejection port my hand got stung and covered in carbon, but otherwise no damage. Id guess just sooty gas vented down between the slide and frame.

Unfortunately the pictures didnt come out real great, and i dont have the case to take more.

Thanks guys.

Yeah out of battery seems to be the most likely scenario.

As a note I do remember hearing the bullet hit the target.

barnetmill said:

I might send the pictures to sig.

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Ill have to check but I THINK the gun is going back to sig for the replacement extractor and a check up....

barnetmill said:

I do not know the sig, but likely being a modern gun has a firing pin block in it to prevent out of battery firing. A high primer could do that but there is a definite firing pin strike on the primer. I would go over the fire control group to make sure out of battery firing pin strikes are not possible. The base of the case is gone and so the barrel likely not locked into the slide when that happened.

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Its got a fairly well-recessed firing pin...i dunno butt end?
I don't know about a blocking safety. Havent really looked into them.

I know for a fact it didn't slam fire as I was firing very slowly at 25yd hostage target and I pulled the trigger before the pop.
The explosion was actually pretty mild, much like a firecracker going off right after you've tossed it. Im INCLINED to think it was a out of battery, simply because that's the most likely incident, tho the cause for the condition I cant say.

mjsdwash said:

I would bet money it was bullet setback. It looks like out of battery because the pressure blew out at the barrel feedramp. I'm basing this on the brass. Blazer brass has very poor neck tension. I have had many rounds setback to where the bullet was entirely in the case, with light finger pressure.
Its so bad, I'm thinking of putting a 20lb spring in a die to push the bullet down on my progressive, so If I accidentally load one, I know. On my Lee 4-hole, I could feel Blazer by the lack of resistance, but on the progressive theres so much distortion in feel it get missed.
I had a similar incident to you with a CZ-75, not quite as severe, but otherwise the same, and Blazer brass setting back was the cause. Take some of your other loads and squeeze them to see.

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the case was lodged fairly firmly in the chamber upon inspection and actually took a good smack from a rod to pop it loose, which possibly/probably bent the rear end out more. When I looked down at it I was looking straight into the hole in the upper right of the case, tho the separation went partway around the case. Im fairly sure it blew out thru the gap between the slide and the barrel face directly in the port and under the extractor, which is fairly large....and now that I've thought about it I wonder if it wasn't strategically placed.

neck tension could well have been the issue. After Del finished the first small batch he gave me a bunch to test and chorono and all were very consistent, but I didn't check the neck tension on more than a couple of them.
The one that popped was from his supply, which were all loaded after I ok'd his specs. Ill ask him if he checked the tension on any of them.

JCooperfan1911 said:

I'm sorry this happened to you. My branch adopted the smaller M18 recently. I'd like to buy one but with 9mm at 60 cents per, no way.

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Thank you
The m-17/18s and the X5 Legion I've shot were all very nice guns. They don't really trip my trigger, but I have no issue recommending them to other folks. Once prices on ammo drop to a reasonable level I think you'd be very well served with an m18

As a side note Im all but positive this wasn't a gun-related issue.

It possible, ill see if he has any of that ammo left at all. I know wed gone thru most of it before the M17 came out yesterday.

Not my gun, ill find out what my buddy says if he sends it back.

1KPerDay said:

some reading you may or may not find useful http://sigforum.com/eve/forums/a/tpc/f/430601935/m/7150091524/p/2

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That looks an awful lot like what the gun and case did when i inspected them. It wasn't blown down the feed ramp as much, but otherwise pretty much the same.