Flintknapper
Member
It's a casting. They are super strong in general but can fail if they have a hidden flaw in the casting (bubble, inclusion, porosity etc) and/or have been subjected to shock loading (dropped, hit hard with something etc) especial shock loading at stress concentration like notch for the priming arm where it appears this crack could have started. That crack could have been started years ago and took many many loading cycles to propagated that flaw or crack into the failure that the OP experienced. It is simply the nature of a casting.
Agreed. Very unusual for one to break at all. I know dozens of folks who (like me) have had their RCBS presses for 4-5 decades and never seen a failure.
It is hard to fathom how it would fail in 'tensile' strength (Vertical Axis) where it is designed to be strongest. I can easily see 'side loading' doing it (dropped or hit by something from the side).
A new one for me...but I am confident it will be replaced with a new one...free of charge.