Weather & Elevation vs consistent load HELP

[Nevrsummr]

I have a load worked up for a favorite rifle that is a fantastic load. I have shot the same exact load for 2 years in many weather conditions with great results. Hunting last weekend my wife shot a 1" group at 450yds with it just to confirm dope at that elevation

. The next day hunting after 2 shots the 3rd shot was way hot . Blew the primer. Bad ejector marks. Stiff bolt. Pic attached.

My understanding is cold weather and high elevation should reduce a loads intensity, Is that wrong? I shot same load in 80* dry hot weather with no issues.

My wife said that the bolt was a little stiff on one of her previous shots as well.

Normal shooting elevation is 2500' and around 50-70*f. Hunting elevation was 7800 and 24*f

No I did not mistake a primer. Highly unlikely that it was a powder overthrow as I have tested the load and did not see pressure signs till 1gr higher. And I check each throw.

 

[ShtrRdy]

my initial guess is a carbon ring has gotten bad enough to cause this.

Something else .... were the cases wet from rain or other moisture?

 

[Nevrsummr]

Maybe like humidity wet, but not precipitation wet

 

[308win]

Carbon ring, they show up fast and screw up the while process. My proven load did the same thing this week. Went from 1.5" vertical at 140pyrds to a 21" vertical, just flat forgot to clean all the carbon out

 

[dfanonymous]

As to the actual question:

Elevation makes your shot go faster or simply increases MV. Air is less dense at altitude than being closer to sea level.

Cold makes air more dense. So it decreases MV.

So, here's the mind boggler that usually causes people to argue. Does MV directly correlate to pressure?

And if so, in your case, was there enough of a MV increase pressures to cause a such pressure signs…?

 

[Nevrsummr]

As to the actual question:

Elevation makes your shot go faster or simply increases MV. Air is less dense at altitude than being closer to sea level.

Cold makes air more dense. So it decreases MV.

So, here's the mind boggler that usually causes people to argue. Does MV directly correlate to pressure?

And if so, in your case, was there enough of a MV increase pressures to cause a such pressure signs…?

Shouldn't all the shooting world / geniuses already have an answer to this? I'm certain this isn't a new problem. Right?

 

[Nevrsummr]

Carbon ring, they show up fast and screw up the while process. My proven load did the same thing this week. Went from 1.5" vertical at 140pyrds to a 21" vertical, just flat forgot to clean all the carbon out

Working on cleaning now. Unfortunately a buddy borrowed my borescope