Seating depths What difference does it make ?

[Ironworker]

Ok we all know how critical seating depths can be with various bullets ,small changes can make tremendous difference in accuracy. My question is why ? If you could fire a rifle and freeze the bullet as it exits the muzzle what distinction will be noticeable on the jacket ? If its jammed into refiling will the jacket be visibly distorted or if its seated as to jump into rifling will it be scar less ? Isn't the bullet swagged to new dimensions during its journey down the bore ? How does the bullet know how deep it was seated ? How does it affect accuracy ? I guess what I'm asking is
What the HELL " ?

 

[Alex Wheeler]

It changes when the bullet exits the muzzle in relation to the barrel harmonics. Thats a vague answer but I do not believe there have been scientific test to determine exactly what happens.

 

[Lapua40X]

It changes when the bullet exits the muzzle in relation to the barrel harmonics. Thats a vague answer but I do not believe there have been scientific test to determine exactly what happens.

I'd concur with that. The location of the bullet within the bore at the optimum point of any cycle within the barrel's harmonic range will influence its accuracy.
We call 'em "nodes".

https://www.google.com/search?q=rifle+barrel+harmonic+cycle&client=ubuntu&hs=S3g&channel=fs&tbm=isch&imgil=gHSvul43LHFciM%253A%253Bi5I9of--ld3dUM%253Bhttp%25253A%25252F%25252Fwww.ozfclass.com%25252Farticles%25252F1%25252Fpsm_2005_03.html&source=iu&pf=m&fir=gHSvul43LHFciM%253A%252Ci5I9of--ld3dUM%252C_&usg=__7qfIpmP5SKfQqa_uDGnaVadSN9U%3D&biw=1231&bih=927&ved=0CCgQyjc&ei=YuX4VPGTMcjxoATFpIKgAQ#imgrc=gHSvul43LHFciM%253A%3Bi5I9of--ld3dUM%3Bhttp%253A%252F%252Fwww.ozfclass.com%252Farticles%252F1%252Farticle1_img5.jpg%3Bhttp%253A%252F%252Fwww.ozfclass.com%252Farticles%252F1%252Fpsm_2005_03.html%3B400%3B222

Have ya ever noticed how some threads rush into comparative discussions about seating depths and omit any consideration of comparative barrel lengths?

 

[Canadian bushman]

It also effects the pressure curve.

In a jump scenario
Think about powder burning and building pressure while the bullet lerches forwards unrestricted hitting the rifling with momemtum.

In a jam scenario
Think about powder burning and building pressure while bullet is jammed firmly into the lands.

Peak pressure and the shape of the pressure curve could vary drastically with differents bullets powder and seating depth.

 

[Ironworker]

It changes when the bullet exits the muzzle in relation to the barrel harmonics. Thats a vague answer but I do not believe there have been scientific test to determine exactly what happens. LINK Didn't WORK

I'd concur with that. The location of the bullet within the bore at the optimum point of any cycle within the barrel's harmonic range will influence its accuracy.
We call 'em "nodes".

https://www.google.com/search?q=rifle+barrel+harmonic+cycle&client=ubuntu&hs=S3g&channel=fs&tbm=isch&imgil=gHSvul43LHFciM%253A%253Bi5I9of--ld3dUM%253Bhttp%25253A%25252F%25252Fwww.ozfclass.com%25252Farticles%25252F1%25252Fpsm_2005_03.html&source=iu&pf=m&fir=gHSvul43LHFciM%253A%252Ci5I9of--ld3dUM%252C_&usg=__7qfIpmP5SKfQqa_uDGnaVadSN9U%3D&biw=1231&bih=927&ved=0CCgQyjc&ei=YuX4VPGTMcjxoATFpIKgAQ#imgrc=gHSvul43LHFciM%253A%3Bi5I9of--ld3dUM%3Bhttp%253A%252F%252Fwww.ozfclass.com%252Farticles%252F1%252Farticle1_img5.jpg%3Bhttp%253A%252F%252Fwww.ozfclass.com%252Farticles%252F1%252Fpsm_2005_03.html%3B400%3B222

Have ya ever noticed how some threads rush into comparative discussions about seating depths and omit any consideration of comparative barrel lengths?