Bullets seat by process of pushing on the ogive curve on the bullet, we then measure them from the end. The process and the measurment don't match up.
I haven't seen a factory seating plug yet that touches the ogive. They're not usually flat, touching exactly on the tip, but they don't come close to the ogive, that I've seen.
However, the greater point is a good one. You should get a bushing that's as close as possible to 0.355", zero your calipers on it and see how much the bullets vary.
Distance from the rifling and seating depth are what dictate pressure. If the bullets are reasonably consistent on the ogive and not at the tip, the simple solution is to use the closest you can find to a 0.355" (9mm
or 11/32) drill bit and drill out the seating plug so it DOES seat from the ogive.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.