I read a post today in the Reloading section on seating depth affecting POI that I postulate was addressed at rifle loads. Green 788 posted the following in response to someone's question:

quote:

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"What you're doing is altering the barrel time of the bullet. When the bullet is seated deeper in the case, it takes it longer to exit the muzzle.

Since we know that the muzzle "whips" with the harmonic whip of the barrel, altering the barrel time will naturally change the point in space where the bullet is released."

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Makes sense to me and I trust Dan's knowledge in this area.

HOWEVER is this such an issue in a 10" T/C bull barrel? Does the whip of a 10" barrel effect POI as much of that in a 22" rifle barrel? Is it significant enough to spend the time (and cost) of working many loads up to test this effect? Has anybody done any extensive seating depth experiments with the 10" T/C? Found that there is significant effects to be had by varying the bullet depth and headspace?

Inquiring minds want to know ! Any takers out there? Thanks folks.

Personally, i would rather believe that it would be more a factor of pressure than "barrel time". Seating depth changes with the same powder charge WILL absolutely affect pressure thus affecting velocity and POI.

A bullet seated .050" off the lands will have a different pressure curve than a bullet seated into the lands even if powder charges are adjusted to give the same velocity.

Just my ramblings (at 1:00 am).....