I am not trying to argue the importance of bullet-to-bore fit, but only to figure out the chambering problem.
I'm not arguing bullet to bore fit either. I'm arguing bullet to freebore fit, which does affect OAL. If the freebore is short, the ogjive will hit the rifling sooner than if the freebore were longer. But in his frustration, the OP is considering sizing the bullet smaller, and this is absolutely the wrong thing to do.