sized brass won't chamber

[Rapier]

Neil,
It looks like you have a bright ring on the body at the shoulder joint and the shoulder itself is dark. This indicates that you have pushed the shoulder back past spec and to the point of expanding the body at the joint. This can be done in several ways, the most common being case lube trapped above the shoulder in the die. The case lube pushes the shoulder back and does not allow the body to travel far enough into the die to reduce the expanded area.

Unless you want to throw the brass away, force the cases, fire them, and you are back to spec. If neck sizing works for you, why fix what ain't broken?
Ed