petemacsydney wrote:Just to confirm I understand correctly though... there should be no problem with having it longer from a danger point of view, but performance may be better or worse dependant on how the rifle/bullet combo works for its COAL?
Is that correct or am I lost?
That's correct, with one caveat.
As covered, seating depth isn't absolute.
(Maybe Aster will do another diagram for this or if you can imagine... I'll do my best to explain well)
As in the diagram, to have both the hunting bullet and match bullet just off the lands the match bullet needs to be seated higher.
If you say the hunting round on the left there is the stated 2.800" the match round on the right will obviously be a lot longer. If you seated the match bullet lower so that the COAL was 2.800" the bullet would be far back from the lands and the bullet would "jump" through the void in the chamber before it reached the lands and went through the barrel. Get what I mean? This is not good for accuracy.
So in this case it's better for accuracy to have the bullet seated higher to be just off the lands and remove the "jump". Even though it's longer than spec it will shoot better and is safe.
Here's the but... Going higher to get closer to the lands is fine, but you don't want the bullet to touch then. And you definitely don't want it too high that it jams into the lands so much the rifling pushes the bullet back into the case.
When the bullet is just off the lands, when the cartridge is ignited the bullet just has to overcome the pressure of the brass neck holding it in place. It's already moving before it touches the barrel and continues through.
When the bullet is jammed into the lands and the cartridge is ignited, the pressure inside the case has to get higher before it's strong enough to push the bullet though the lands which are holding it in place. This increases the pressure inside the cartridge which is a safety concern.
You with me?
Short version, assuming that's all clear... If you need to seat your SST's to be 2.810" instead of 2.800" so they're just off the lands, that's perfectly fine.