Cartridge blows up

[midatlantic]

At the range today I fired my home made 80 percent 1911. 3000 rounds thru it so far.

 

press trigger, boom, base of magazine blows out. Fortunately it was the last round. I feel to find wound, none, and look at gun. 

 

Intact, but the slide was jammed closed. Took it home, remove the bushing, whacked the back of the slide with a rubber hammer, it slide off and out popped the burst cartridge In photo.  
 

So I’m wondering what happened. An overcharge? Could be of course.  the cartridge was loaded thru a Mk 7 auto drive w powder sensor that stops press if overcharge or under charge, and tests shows it works well. Load is 200 swc w 3.6 of clays. My steel load. 

 

Or, brass fatigue in the case? Cause I wonder why an over charge would blow out the base? Opinions?

 

Seems to me barrel looks fine.  Anything I should look for?

Edited September 24, 2021 by midatlantic

[Guy Neill]

The blow-out in the case suggests it was not fully supported by the barrel.

 

How about a photo of the barrel feed ramp area with a round in the chamber.?

 

 

 

 

[Jim Watson]

The blanked primer says much pressure to me.

The blown case says much pressure over a generous feed ramp.

The A-USA head stamp says cheesy brass.  

[midatlantic]

Here’s the barrel w cartridge 

[ChuckS]

See if you can take a picture that shows the cartridge and the feed ramp

 

like this one:

 

[Guy Neill]

The last photo shows the feed ramp in the barrel extends such that you can see casing ahead of the extractor groove, meaning an unsupported area.

 

You should not see any casing in front of the extractor groove to fully support the case during firing.

 

If you put the blown case in the chamber you will find that the blow-out exactly matches the area unsupported.

[ltdmstr]

2 hours ago, Guy Neill said:

The last photo shows the feed ramp in the barrel extends such that you can see casing ahead of the extractor groove, meaning an unsupported area.

 

You should not see any casing in front of the extractor groove to fully support the case during firing.

 

For most .45s, it's not uncommon to have a small amount of the case ahead of the extractor groove that's unsupported.  In fact, that's normal for an unramped barrel.  And with a normal charge that's not a problem because the case web is much thicker there than it is for the rest of the case wall.  But here, it looks like the unsupported area is excessive, and probably extends to the thinner portion of the case.  That, combined with excess pressure, probably rendered the results in the photo.  Another possibility is a stuck firing pin which could have ignited the primer before the gun was fully into battery.  That would also explain the hole in the primer.

[ChuckS]

Uh, guys, the second picture in my above post was just something I found on the net to show the OP what kind of picture would help us understand his problem. He has not replied yet  

[ltdmstr]

3 minutes ago, ChuckS said:

Uh, guys, the second picture in my above post was just something I found on the net to show the OP what kind of picture would help us understand his problem. He has not replied yet  

 

Ok, duh.  Not sure how I missed that.

[Guy Neill]

You mean I'm supposed to read the articles and not just look at the pictures???

 

But I would be surprised if his barrel looks different than the photo given.

 

 

[midatlantic]

Another possibility is a stuck firing pin which could have ignited the primer before the gun was fully into battery.  That would also explain the hole in the primer.

 

 

I think that was it, as when I took the gun apart the firing pin was indeed stuck....and my recollection is the cartridge ignited a bit earlier than it should.  so, replace firing pin...what about the aperture? How to test that, other than seeing if new firing pin sticks?

 

 

[ima45dv8]

Did you take the firing pin out? A broken FP spring can happen if dry fired a lot, and can cause it to be stuck/jammed forward.

I use to wonder why recoil springs came with a spare FP spring (Wolff, I think?) until I had one break.

[IHAVEGAS]

19 hours ago, midatlantic said:

Load is 200 swc w 3.6 of clays. My steel load. 

 

For what it is worth, I was standing behind and watching a shooter when he fired off an overcharged Bullseye load , Les Baer premier 2 45. 

Grips (oem wooden) blew apart, magazine blew out the bottom of the gun, rounds in magazine were stair stepped with the lead in the top bullet being pushed back quite a bit and the bottom bullet almost none or not at all, smoke cloud enveloped the shooters head, shooter was not hurt and LB pronounced the gun aok when they examined it. I don't remember what the brass looked like or if we found it.  

 

Clays has been used forever in mouse fart 45 loads, but, it is the fastest powder that I've seen show up in my reloading manuals & it often is left out presumably because it is thought to be too fast & in your case the difference between a max charge and a minimum charge (per my Lyman manual) is only 0.5 grain. 

[GrumpyOne]

4 hours ago, midatlantic said:

Another possibility is a stuck firing pin which could have ignited the primer before the gun was fully into battery.  That would also explain the hole in the primer.

 

 

I think that was it, as when I took the gun apart the firing pin was indeed stuck....and my recollection is the cartridge ignited a bit earlier than it should.  so, replace firing pin...what about the aperture? How to test that, other than seeing if new firing pin sticks?

 

 

With the stuck firing pin, it fired out of battery, which would blow out the bottom of the case like that.

[Toolguy]

Clean and inspect the firing pin channel, check for close fit of firing pin to hole, and free manual operation of firing pin when replaced.

[IHAVEGAS]

1 hour ago, GrumpyOne said:

With the stuck firing pin, it fired out of battery, which would blow out the bottom of the case like that.

 

Is the area where it blew ever supported?

 

40 fired in 45 barrel 

 

[GrumpyOne]

Just now, IHAVEGAS said:

 

Is the area where it blew ever supported?

 

40 fired in 45 barrel 

 

In certain barrels, that area is much more supported. Look at an old 38 auto barrel. It was much less supported than the current 38 super barrel. 

[TONY BARONE]

Bullet set back?

 

[Jim Watson]

Slamfire by a stuck firing pin would require several things to be just right - or just wrong - at the same time.

I think the firing pin is now stuck because the blanked primer blew a piece of cup and crud back down the firing pin tunnel.  

[TONY BARONE]

I would think that a gun would not feed with the firing pin protruding from the breech face.

 

[Jim Watson]

The only case I saw, a Gold Cup firing pin was protruding nearly a quarter of an inch, stopped only by the spring stacking solid.

No feeding in front of that.

You would have to assume something sticking the firing pin with normal .040-.060" protrusion AND an inertia feed to get the round in front of the firing pin and extractor AND something stopping the round entering the chamber with a lot of case wall exposed AND the extractor snapping over the rim leaving enough force to fire the primer.  Right.

[shred]

Overcharged rounds look and act just like that when they blow.  Occam's Razor suggests overpressure some way, some how.  Too much powder, too much bullet, too-deep-set bullet, who knows.

 

More than likely your extractor has no tension now either.  That always seems to happen when a case blows.

 

This one chronoed at something like 1200 fps when it blew several years ago.  Loaded on an 1100/Mark 7 with 231.  You may notice a bit of a resemblance.

 

 

[midatlantic]

Yeah, that’s close.  Tho the primer remained in mine. Also, the firing pin was sticking out when I disassembled. Cause or effect? Cleaned out the firing pin channel, replaced the spring and pin which was scorched just aft the tip, and would not rub out w alcohol. That spot is a bit rough. Will check extractor. 

[zzt]

On 9/25/2021 at 11:07 AM, IHAVEGAS said:

Clays has been used forever in mouse fart 45 loads, but, it is the fastest powder that I've seen show up in my reloading manuals & it often is left out presumably because it is thought to be too fast & in your case the difference between a max charge and a minimum charge (per my Lyman manual) is only 0.5 grain.

 

Clays is well know to get spikey near max.  So is Int Clays, which is why you will never see that in a loading manual.  I'd put Alliant Clay Dot in the same category.  Just substitute Alliant e3 for your Clays load.  It is cleaner and consistent from lot to lot.  You cannot say that about Clays.  Also, e3 has no temperature sensitivity and exhibits none of Clay's spikeyness.