I'm sure geometry is relevant in resect to the bullet shape, ogive shape, length etc. but Physics is equally at play here namely the distance between shell holder & seating die plug. Of the 50 or so sets of dies that I have, not one of them have a "ring" for seating contact, every one of them is a shaped ,closed end "plug" that accommodates one bullet shape or another be it a flat point, spitzer or round nose. The physics of the press is that the ram has an equal travel distance every time and the die setting is equal for every action of the press. the distance between the shell holder & die plug is static unless the operator makes an adjustment...the OP claims not to have made any adjustment.
As you say, the bullet geometry is relevant but it does not cancel out the physics distance between shell holder & plug. Of course I am assuming that the OP is using a correct seating plug for the shape of bullet nose he is loading and had it correctly set to contact the bullet tip when seating ( if he isn't then I concede LOL). The geometry of the bullet length is immaterial in the OAL, the geometry of the bullet ogive& tip are. The ogive to bullet tip distance can change but that wont change the OAL, the bullet tips cannot exceed the distance between holder & die plug inside tip. Ogive shape can change OAL tho...a fatter ogive curve will contact the plug sidewalls before the tip of the slug does and that pushes the slug, not the bullet tip so it can only be the same length or shorter in all cases. If the ogive was a longer slimmer version the OAL still cant be "longer" because the bullet tip becomes the push point...and that OAL cannot exceed the original setting of the die to shell plate distance...not ever...Physically impossible to fit a longer distance in a solidly set shorter space.
Dude, nice theory, for being so completely wrong.
The contact of the seater inside the die, on the bullet itself, is a ring of fixed diameter, the bullet nose goes up inside it, else it would only need a flat bar (much cheaper for the die makers to provide, but they put the hollowed out one in there...think on that!).
Or, are you saying that you have a specific seating plug in each die, tailored to fit only one bullet shape? Because if you have not had custom plugs made, you are working from a really wrong set of assumptions!
If the nose of the bullet is longer and narrower, then there is more of the bullet sticking out front, and you get a longer OAL at exactly the same die setting as worked with the shorter fatter bullet.
If you really want to know why I say that your die is contacting the bullet in a ring of fixed diameter, paint up a bullet with a Sharpie Marker and rub it around in the seater plug. Do the same with a pointier Rifle bullet of the same diameter. See how much difference there is in the amount of bullet ahead of the contact ring that will mark itself out in the Sharpie you applied.
For the OP's purposes, I think he's being a little too tight-arsed about the tolerances he's trying to achieve for what he is making. As long as they are reasonable loads, and they fit in the magazine, he is likely going to be very happy with them. If he was expecting Olympic Target accuracy, he needs to buy better bullets!
