Weather & Elevation vs consistent load HELP

Nevrsummr · Monday at 4:18 PM

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 · Monday at 5:24 PM

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 · Monday at 7:48 PM

Maybe like humidity wet, but not precipitation wet

308win · Monday at 8:07 PM

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 · Monday at 8:28 PM

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 · Monday at 10:10 PM

dfanonymous said:
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 · Monday at 10:11 PM

308win said:
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

Critter Picker · Monday at 11:50 PM

Don't forget to check firing pin. If primer blew there could be damage.

Bang4theBuck · 2024-11-05T05:11:41-0600

Just for my own information, do.we not have to make a distinction between down range velocity and muzzle velocity? The things they can alter muzzle velocity are pressure differences inside the chamber (temp sensitivity in powder, bullet jamb condition, carbon ring, etc). The things Density Altitude will affect ballistics (external to the barrel). So whatever if your load was tested at warmer temps, amd the charge didn't increase, then the issue is not related to elevation temperature, or humidity.

If cleaning the barrel.doesnt solve it, I would pull a couple bullets and check the charge. Also, I've seen excessive dampness from cleaning left in the chamber as well as a gun that got wet both al.ost lock up the bolt. If your charge was on the ragged edge, any moisture in the chamber could increase pressure significantly.

Definately keep.us posted on your findings.

med358-boise · 2024-11-05T05:47:50-0600

Just be prepared that you may never find out. This could be an anamalous event and the "sample" is now destroyed.

Nevrsummr · 2024-11-05T08:40:20-0600

The barrel could have got damp only from snow on the ground getting into it. Or humidity- say from warm truck to 20* cold outside. There was no precipitation. My wife was packing the rifle so I dont know for sure. It does have a muzzelbrake so that makes it harder to plug up a barrel. And 2-3 shots had just been fired previously to that. (W/ stiff bolt)

Say she did get some moisture in the barrel. A small amount from snow. How many shots does it take to clear that? Is it reasonable to think that 3 shots would be hot? The last one being hottest?

The gun hadn't been cleaned for a while.

Thanks for all your input & help here

DJ Morrison · 2024-11-05T08:44:14-0600

i would guess carbon ring also..

emp1953 · 2024-11-05T09:29:01-0600

Nevrsummr said:
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 elevationView attachment 614257. 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.

Could you have run into a "cold weld" situation?

Brathany · 2024-11-05T09:37:52-0600

I have popped primers when liquid/oil was present in my barrel.
I have ruptured a case when the neck clearance wasn't enough. Carbon ring will reduce clearance.

Weather & Elevation vs consistent load HELP

Nevrsummr

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ShtrRdy

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Nevrsummr

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308win

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dfanonymous

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Nevrsummr

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Nevrsummr

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Critter Picker

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Bang4theBuck

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med358-boise

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Nevrsummr

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DJ Morrison

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emp1953

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Brathany

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