So, I had an exciting evening. I was shooting my USP45 without any problems when a round exploded inside the chamber. The case extracted and ejected just fine and the bullet struck the target. This load is approaching max for standard pressure .45, but I have fired many thousand rounds of this exact load without issue. 

 

The magazine blew out of the mag-well and I felt a bunch of crap hit my face(this is why we wear eye-pro kiddies!). So far, the gun seems fine, but I have to strip it down and clean it out before I'll feel confident firing it again.

 

Here are pictures of the problem round:

 

 

 

 

 

 

 

After having a chat with Old School, we're thinking it was a crap case that was just due for failure. That coupled with a somewhat hot load resulted in the case failure and resulting boom.

Wow. Glad you are ok. I bet it was the crappy HK. Lol..jk

Wow. Glad you are ok. I bet it was the crappy HK. Lol..jk

 

LOL! I'll bet that crappy HK is why I still have hands

Glad I never have to worry about that happening to me. I don't shoot enough

What was the load?

5.6gr W231, 230gr plated round nose, 1.260 oal

 

Highlight above text for load data. Use it at your own risk!

I cant see the pictures on my work computer, but i've read something similar to this in the past, case seperation and blew the magazine out... just a peice of brass that was weak.

 

 Did the case split down the bottom toward the rim?

Looking at it I will guess range pickup brass that had oxidation there where the zinc leached out and left you with a porous copper spot.

 

It's the primary reason I don't like wet tumbling with ss media and lemishine. It hiss those funky orange black spots.

How many times had that piece been reloaded?  My FIL who taught me to reload sorts his brass by number of times fired and discards straight walled pistol brass after 8 or 9 loadings even if they look fine.

Possibility of a double charge? Can the case hold a double charge of whatever you're using? The reasons I ask are:

 

1. Not familiar with your gun but is the entire case head supported? Looks like the case blew out over the unsupported part of the chamber.

2. The primer looks like it was flowing back over the firing pin and that its backing out of the primer pocket.

3. I've loaded a whole bunch of 45 ACP over the past 40 years and any case failure I've seen like that was due to overpressure.

The fact that it was a 50 year old piece of brass (notice the WCC 63 headstamp) and its advanced state of oxidation just reinforces my belief in reloading only newish, shiny (by corn cob and Flitz) range pickups. Direct into the scrap bucket for brass that color, thank you.

Wha? Only Glocks can KB! No way could this happen to a HK ! This is nothing but a vicious Internet rumor!

 

Glad you are OK bro.

 

Did you check your barrel for a bulge?

 

Did you check your draws for poo?

Yikes  Glad your ok. 

The fact that it was a 50 year old piece of brass (notice the WCC 63 headstamp) and its advanced state of oxidation just reinforces my belief in reloading only newish, shiny (by corn cob and Flitz) range pickups. Direct into the scrap bucket for brass that color, thank you.

The fact that the brass is 50 yrs old has nothing to do with it. I have some WCC67 factory ammo and when I shoot it there is really no difference from that brass and brass from ammo made yesterday. Don't know if that's oxidation or poor lighting and soot from the kaboom. The rim and extractor groove look to be in good shape. I've safely used brass worse shape.

 

Now it could have been a weak case but that wouldn't be my first diagnosis.

Looking at it I will guess range pickup brass that had oxidation there where the zinc leached out and left you with a porous copper spot.

It's the primary reason I don't like wet tumbling with ss media and lemishine. It hiss those funky orange black spots.

 

This is what I'm thinking. I need to spend more time inspecting brass.

 

How many times had that piece been reloaded?  My FIL who taught me to reload sorts his brass by number of times fired and discards straight walled pistol brass after 8 or 9 loadings even if they look fine.

 

Unknown. This was a range pick-up.

 

Possibility of a double charge? Can the case hold a double charge of whatever you're using? The reasons I ask are:

1. Not familiar with your gun but is the entire case head supported? Looks like the case blew out over the unsupported part of the chamber.
2. The primer looks like it was flowing back over the firing pin and that its backing out of the primer pocket.
3. I've loaded a whole bunch of 45 ACP over the past 40 years and any case failure I've seen like that was due to overpressure.

 

Here are pics of the chamber:

 

 

 

The primer shows no signs of over-pressure in person, it just looks that way in the photo. The reason I disagree with overpressure, is that I would have expected some bulging of the case. In this case it appears more that the case sheared away in a specific spot with little stretching of the brass itself.

 

The fact that it was a 50 year old piece of brass (notice the WCC 63 headstamp) and its advanced state of oxidation just reinforces my belief in reloading only newish, shiny (by corn cob and Flitz) range pickups. Direct into the scrap bucket for brass that color, thank you.

 

Yup. This will be my MO from now on.

 

Wha? Only Glocks can KB! No way could this happen to a HK ! This is nothing but a vicious Internet rumor!

Glad you are OK bro.

Did you check your barrel for a bulge?

Did you check your draws for poo?

 

 

Thanks, I'm glad too! [HK Kool-aid]I do wonder how another plastic-framed .45 would have handled a similar failure vs the almighty USP[/HK Kool-aid]

 

No barrel bulge or cracks. Drawers appear clean

Just finished stripping the gun down and going over every inch of it. I am unable to find a single crack, chip, bulge, or any other unpleasant thing. I'm confident that it is ready to roll but it'll be placed on safe duty until I send another couple hundred rounds through it and ensure it's g2g back in the nightstand. Good thing I have lots of HKs!

Weak brass. I have some .45 brass that has been shot so many times that the headstamp is unreadable, .45 is a low pressure cartridge compared to a lot of other things we shoot so the brass can last a very long time, but the corrosion thing combined with what looks like an unsupported chamber will get you eventually.

It does look like an unsupported chamber based on the brass but I thought the HK45 was fully supported, which is why it's able to shoot .45 Super right out of the box. You'd have to pull the barrel out and drop in the cartridge and look at the gap, the pics with the slide assembled don't help. (EDIT: Whoops, you said USP .45. So perhaps.)

 

Is there any chance it was slightly out of battery?

 

I had a very similar KB with my 1911 and I've never been able to fully explain what happened.

Ouch! I'm glad you're okay. From the headstamp, it looks like the brass is old and has been reloaded several times. I need to sort my own brass stash and set aside those that look worn out.

Glad to hear no personal injury.  This is something I have always been concerned of when people tell me about reloading.  The way I see it the companies that make ammo do it to make money (like duh!).  But my point is that I would imagine that they have engineers that calculate the minimum wall thickness for the pressure the round will see and add some safety margin.  I doubt they add extra metal to provide extra strength for multiple uses of the case where they get no compensation for that future usage.  Thus, I would expect to see more and more of these issues as companies strive to minimize cost while maximizing income.

Nah, they want to have as much margin of safety as they can when they make the brass because if they screw up the loading themselves by a little bit they want all the margin they can. If they wanted to save money they'd load steel cases. 

Nah, they want to have as much margin of safety as they can when they make the brass because if they screw up the loading themselves by a little bit they want all the margin they can. If they wanted to save money they'd load steel cases. 

I agree 100% there is a safety margin, good engineering requires that.  What I question is what exactly is that safety margin.  I would venture to say it is much lower than it was ten or twenty years ago.  I am sure they do detailed analysis to determine how they can safely thin the walls to save money.  Think about how many billions of rounds are produced and what a few fractions of a cent in production cost goes right to the bottom line.  Its probably a lot cheaper to buy insurance than to make thicker cases.

I'd think the opposite is true, they are a hell of a lot more likely to be sued today then 20 years ago. 

 

Keep in mind that making the walls thinner might actually be harder during the manufacture process, plus because the external dimensions don't change (or guns and mags may not work right) that means you now have more case volume which means you might have lower pressures and they need to up the powder charge to make the same velocity and so on and so forth. 

I'd think the opposite is true, they are a hell of a lot more likely to be sued today then 20 years ago. 

 

Keep in mind that making the walls thinner might actually be harder during the manufacture process, plus because the external dimensions don't change (or guns and mags may not work right) that means you now have more case volume which means you might have lower pressures and they need to up the powder charge to make the same velocity and so on and so forth. 

That is a true statement, but the flip side is that the actual cost of the metal is also much much higher than it was 20 years ago.  As far as case volume I don't think it would be impacted significantly by the slight thinning of the walls.  Even if it were could they not make up for it by seating the bullet a fraction of an inch deeper in the case to maintain the same case volume?

 

Think back 20 years ago how things like soda cans were much thicker walled than they are today.  The same goes for 2 liter bottles, car fenders, and just about any other form of packaging you can think of.  Maybe ammunition makers have not worked on this, but I bet they have.  If they have not yet, you can bet they will be as costs continue to rise.

Well that should be an easy theory to prove, all you have to do is measure some wall thickness between older brass and newer brass. 

Good idea someone that has some should do that.  I would imagine you would need to compare across a given brand as I imagine it varies by brand to some degree.

If I'm bored I'll go through my 5 gallons of .45 brass.