338LM problem

[UA SOF SNIPE]

I load the cartridges myself, I have checked the charge and the geometry of the cartridge case and the seating of the bullet.
As the temperature increases, the calculated bullet speed is correct, but ES and SD begin to increase.
If anyone has had this problem, please share your experience.

 

[918v]

That’s normal if you’re maxed out on pressure. I’ve seen it in every cartridge I load for.

 

[UA SOF SNIPE]

That’s normal if you’re maxed out on pressure. I’ve seen it in every cartridge I load for.

But I didn’t see any signs of high pressure; the bolt groups operate smoothly and in normal mode.

 

[UA SOF SNIPE]

That’s normal if you’re maxed out on pressure. I’ve seen it in every cartridge I load for.

Do you recommend finding the required powder charge at lower pressures?

 

[Huskydriver]

What kind of powder? Double base or single?

 

[918v]

But I didn’t see any signs of high pressure; the bolt groups operate smoothly and in normal mode.

Signs of pressure appear when you’re way over max, like mid 70’s.

 

[918v]

Do you recommend finding the required powder charge at lower pressures?

Yes. What load are you running? How close to the lands? Same brass as whatever data you’re using?

 

[UA SOF SNIPE]

What kind of powder? Double base or singl

I don't know for sure. I use gunpowder from military ammunition.
And if it’s not a secret, what is the difference between single-component and two-component powders?

 

[UA SOF SNIPE]

Yes. What load are you running? How close to the lands? Same brass as whatever data you’re using?

the bullet is indented from the rifling 100 percent.
I checked it with a marker more than once. The cartridge case was the same one I was looking for charge parameters

 

[918v]

I would redo the load with a healthy amount of bullet jump. That way it will be environmentally stable.

 

[918v]

I don't know for sure. I use gunpowder from military ammunition.
And if it’s not a secret, what is the difference between single-component and two-component powders?

Double base powders are generally more temperature sensitive than single base powders. They contain nitroglycerin in addition to the other stuff. They produce more energy and velocity.

Recently powder manufacturers developed temp stable double base powders but the tech is not widely available. There are a gazillion different powders out there.

 

[UA SOF SNIPE]

I would redo the load with a healthy amount of bullet jump. That way it will be environmentally stable.

The bullet does not touch the rifling, this is 100 percent, each assembled cartridge is measured with a bullet comparator. The shoulders of the case are the same, there should be no problems with this.

 

[UA SOF SNIPE]

Double base powders are generally more temperature sensitive than single base powders. They contain nitroglycerin in addition to the other stuff. They produce more energy and velocity.

Recently powder manufacturers developed temp stable double base powders but the tech is not widely available. There are a gazillion different powders out there.

That is, simply put, two-component powders provide more energy but are more sensitive to temperature changes.
And one-component ones are less energetic, but stable to temperature.
It just baffles me that this happened to my charge, which has never bothered me.
But two-component powders, having a greater temperature dependence, can give the effect I described earlier.?
By the way, my temperature shift is 0.5 m/s per 1°C, do you think this is a one-component gunpowder or rather a two-component one?

 

[UA SOF SNIPE]

So what bullet, powder, brass and primer are we talking here?? Need to know 4 components the how far off the lands are you??

I use a Peterson gun casing, Federal GM 215 capsule.
Bullet 300 SMK
I don’t know the powder from the company, the weight of the gunpowder is 89.3 grains.
Initial bullet speed 823m/s at 21°C
Bullet offset from rifling 0.0035"

 

[UA SOF SNIPE]

WOW I would NEVER shoot a powder I didn't know what it was. How do you know the burn rate or even if it is compatible for the .338 LM?
Having said that it sound like you using a Retumbo burn rate powder.
Here is my load and I don't have any issues in the summer and it gets well over 100 here.
AXMC 29in 1-9.3 Twist barrel
Brass Nosler
Bullet 300 Berger Hybrid
Powder Retumbo 90.5
Primer Fed 215M
AVG FPS 2787
SD 8.4/ ES 17.7

This gunpowder is in 338LM cartridges with the same bullet weight of 300 grains.
In a standard army cartridge, the weight of gunpowder is 88.8 grains, my weight is 89.3 grains, everything is made with the same components, but I selected the recipe for my specific rifle, that’s all.

 

[918v]

That is, simply put, two-component powders provide more energy but are more sensitive to temperature changes.
And one-component ones are less energetic, but stable to temperature.
It just baffles me that this happened to my charge, which has never bothered me.
But two-component powders, having a greater temperature dependence, can give the effect I described earlier.?
By the way, my temperature shift is 0.5 m/s per 1°C, do you think this is a one-component gunpowder or rather a two-component one?

I think in FPS and Fahrenheit, and yours translates to .5 FPS per deg, I hope. I once developed a 308 load using either CFE223 or 2000MR I forget, but that was a double base powder and I observed a .5 FPS per degree shift. But other people here reported two to three times that. So mine was pretty low. Honestly I don’t think anyone can tell based on just the velocity shift alone.

 

[UA SOF SNIPE]

WOW I would NEVER shoot a powder I didn't know what it was. How do you know the burn rate or even if it is compatible for the .338 LM?
Having said that it sound like you using a Retumbo burn rate powder.
Here is my load and I don't have any issues in the summer and it gets well over 100 here.
AXMC 29in 1-9.3 Twist barrel
Brass Nosler
Bullet 300 Berger Hybrid
Powder Retumbo 90.5
Primer Fed 215M
AVG FPS 2787
SD 8.4/ ES 17.7

By the way, bro SD 8.4 is a very large spread. Statistically, many of your shots miss the calculated values.
When my SD is more than 2.5, I already know that the cartridge will not work at long distances.

 

[918v]

This gunpowder is in 338LM cartridges with the same bullet weight of 300 grains.
In a standard army cartridge, the weight of gunpowder is 88.8 grains, my weight is 89.3 grains, everything is made with the same components, but I selected the recipe for my specific rifle, that’s all.

The difference is your bullet is jammed in the lands which creates a different combustion quality.

 

[UA SOF SNIPE]

I think in FPS and Fahrenheit, and yours translates to .5 FPS per deg, I hope. I once developed a 308 load using either CFE223 or 2000MR I forget, but that was a double base powder and I observed a .5 FPS per degree shift. But other people here reported two to three times that. So mine was pretty low. Honestly I don’t think anyone can tell based on just the velocity shift alone.

I'm talking in metric measurements meters per second and degrees Celsius.

 

[UA SOF SNIPE]

The difference is your bullet is jammed in the lands which creates a different combustion quality.

I fully understand what you are talking about. But I am saying once again that the bullet in my load does not touch the rifling of my rifle specifically.
Before finding a load of gunpowder, I measured the maximum length of the bullet extension in the assembled cartridge. And immediately from the rifling I went to the bottom by 0.005" But looking for a good cluster of bullet dispersion, I went even lower from the rifling in the barrel.
Therefore, I can’t rest the bullet against the rifling of the barrel, given the burnout of the bullet entrance

 

[918v]

Sorry I misread your post. But you’re still real close. That amount of jump is nothing. If you open a new box of bullets you may have a hard jam or be farther away. I would back off 20-50 thou.

 

[918v]

I'm talking in metric measurements meters per second and degrees Celsius.

I know, but i think there are 3 feet in a meter and three deg Fahrenheit in a deg of Celsius. I dunno I’m American.

 

[UA SOF SNIPE]

Sorry I misread your post. But you’re still real close. That amount of jump is nothing. If you open a new box of bullets you may have a hard jam or be farther away. I would back off 20-50 thou.

my indentation is 0.035"

 

[918v]

Then back off the powder charge.