Velocity=Harmonics=Accuracy node?

[thefitter]

If you develop a accurate load with a specific bullet for a specific barrel can you count on another comparable accurate load with a different powder as long as you have the same velocity?

Or- once I find the velocity that my barrel likes for a given bullet it does not matter what powder I use to achieve that velocity, I should still have an accurate load, right?

Isn't that what a harmonics node is?

Thanks

 

[Alex Wheeler]

In my experience a node is good for one combo of components. Change anything and the optimum load usually changes as well. Try 4 different powders and likely there will be 4 different velocities they want to shoot at. They may be close though. JMO

 

[amlevin]

All the reading I've done on the topic seems to show a consensus that accuracy nodes are determined by the transit time of the shock wave in a barrel, along with the barrel harmonics due to material and shape.

This logically could mean a different shock wave propagation with different powder. This could lead to different barrel behavior regardless of same velocities.

I know that my favorite rifle has an accuracy node changes with changes in powder even though the bullet remains the same. One powder is more accurate at slower speeds and several others require higher velocities to maintain the same accuracy at same distances. Speed differences can be over a range of 200-250 fps.

For me, I've finally settled on One Bullet, and One Powder for this rifle. They just work real nice together from short range to "way out there".

I may be way off base in my understanding of the physics involved but that's just what I've found in my world.

 

[Nomad47]

Agree with Amlevin. According to Chris Long's OBT (Optimum Barrel Time) papers and QuickLoad, different powders (due to their different burning rates) take differing amounts of time to reach the end of the barrel for a given velocity.

 

[Win94ae]

Harmonics are just one part of the puzzle; the other piece is how consistent the powder burn.

Other than the burn consistency, another powder will have a differing pressure curve therefore differing harmonics.

 

[thefitter]

Harmonics are just one part of the puzzle; the other piece is how consistent the powder burn.

Other than the burn consistency, another powder will have a differing pressure curve therefore differing harmonics.

I'm just starting to try and understand pressure curves.