Ok, I will bite.... Fortunately I have never done this so I have no real world experience. Just thinking about the question, I would say first off that the capacity of the case would matter as a very large magnum case would build up less PSI than a small case. You took care of the bullet size (kind of) by stating it would take 25 lbs of force to get it out of the case mouth.
My guess: (A)
When the primer is fired, the gas has to go somewhere and the pressure should be plenty to move the bullet. However, as soon as the bullet moves enough to break the case mouth seal the gas will escape around the bullet and pressure will drop quickly. The only question is if it will move forward with enough force to jam the bullet into the lands?
I would answer (B) as I think the pressure will drop quickly, but I have seen guys who missed a powder charge when loading shotgun shells. Just a 209 primer will blow 1 oz of shot 10 to 20 feet out of the barrel of a shotgun so I rather suspect a rifle primer will have enough force to jam a bullet into the lands.
Bart, You have a lot of shooting experience so I assume you know the answer......... interesting question, just don't leave us hanging too long