Can you guess what caused this failure?

[xsn10s]

We'd, or whoever was there, would have to see the ammo and target to get closer to what actually happened. According to that Norma page you'd have to have a couple of hundred rounds of a "7mm Super Magnums" to get to proof pressures. If proof pressures blew that barrel up then there were other issues with that barrel.

 

[Shane Lindsey]

According to Norma not as many as you may think.
View attachment 283272

I don't think the word copper solvent exists in many of the services. I know I put thousands of rounds through a rifle and only used CLP. Last I checked, that barely even cleaned carbon...

My vote for what it's worth was a bore obstruction in the form of 325 WSM...

 

[Muddyboots]

Carbon Ring, I saw it right off

BB: left the Teslong in barrel looking for the carbon ring I bet!

 

[Muddyboots]

My vote for what it's worth was a bore obstruction in the form of 325 WSM...

The way the entire barrel both grooves and lands are "smeared" heavily with copper seems to suggest wrong cartridge shot like a 325WSM.

 

[ButterBean]

BB: left the Teslong in barrel looking for the carbon ring I bet!

 

[Muddyboots]

Somebody help me out? What the heck is a "7MM Super Magnum"? Is it a "Super Creed"?And how do you exceed max pressure after 30 rounds?

My Sendero is never cleaned until maybe 100+ rounds. Thank God for 3 Rings of Steel!

 

[lancetkenyon]

In a big chunk that would look like a bullet

 

[ButterBean]

Somebody help me out? What the heck is a "7MM Super Magnum"? Is it a "Super Creed"?And how do you exceed max pressure after 30 rounds?

My Sendero is never cleaned until maybe 100+ rounds. Thank God for 3 Rings of Steel!

I've shot my 308 500 plus rounds and never cleaned, and if there is a "Super NeedMoor" I'm done

 

[xsn10s]

Somebody help me out? What the heck is a "7MM Super Magnum"? Is it a "Super Creed"?And how do you exceed max pressure after 30 rounds?

My Sendero is never cleaned until maybe 100+ rounds. Thank God for 3 Rings of Steel!

Look at the "Norma page" #62 post. It's probably referring to 7 RUM or something like that.

 

[Coyote Shadow Tracker]

How many rounds do you have to put through a barrel to have enough copper buildup to cause overpressure? Thousands with out cleaning? Look at rifles used in combat and how many rounds are fired without cleaning?

Well if you see how much copper was on the lands it could have only come off of the last bullet fired. Most likely was not a .308 bullet loaded in the 300 caliber barrel, but a larger diameter bullet to have that much copper wear off. I originally went with a squib, but after all the comments about copper and examining the barrel lands with all that "Fresh Looking copper" I have to go with oversize bullet diameter.

 

[Baker Alvin]

Thankfully, You are ok. In all my years of reloading, I had loaded 100 rounds and went to check point of impact. I only used the first round. I never had a reaction like it before and never need another. The gun smoked out of every port. One can never be to careful. After getting home and pulling a bullet, weighing the charge, it was a very obvious the issue. so it was pull 98 more bullets and count my blessings each time.
We all need to run a cleaning rod thru the bore before shooting. Don Lewis, long time writer, for The Pennsylvania Game News, relates in the book he wrote, of the time mud daubers, built a nest in his rifle barrel between his times of using a rifle.

 

[skipglo]

I just noticed it is a fluted barrel, flutes cut to deep?

It looks to me that the failure ( obstruction) or pressure started just at the front of the scope before it was near the fluting...note the bulge..wrong caliber or bullet possibly...OP...were you using reloads?

 

[skipglo]

Well if you see how much copper was on the lands it could have only come off of the last bullet fired. Most likely was not a .308 bullet loaded in the 300 caliber barrel, but a larger diameter bullet to have that much copper wear off. I originally went with a squib, but after all the comments about copper and examining the barrel lands with all that "Fresh Looking copper" I have to go with oversize bullet diameter.

My thoughts exactly....didn't read far enough before I commented!

 

[SteveBurton]

I did that to my 300WSM in my early days of reloading. Instead of grabbing the H4350, I grabbed the H4198 for my 45/70. Back then the reddish-brown labels were very close in color. Being in a rush to get to the range I made a mistake. First shot and boom! Split the barrel, blew it off of the receiver, split the stock, seized the bolt in the receiver, broke the scope in half and launched the objective bell down the firing line. Miraculously all that happened to me was a fiberglass splinter in my finger. Luckily my left hand was supporting the rear of the stock or I'm sure I would have lost it.
Needless to say that imprinted a lasting impression in my brain about attention to detail when reloading. I get razzed all of the time for how long it takes me to reload bullets now but I'll take that over an injury any day. Glad the shooter was ok.