Kilibru ---- The cracks found at the rear of lockplates are caused by "set back" at the head. The wood can become oil soaked & not support the recoil / the stock wasn't inletted properly/and or glassed , allowing the action to slam back against the stock. When the recoil isn't taken up at the head of the stock, it is transfered to the lockplates which transfer the recoil to the immediate area at the rear of the plates. This action drives the plate into the stock and causes spliting inasmuch as the plate acts as a wedge. Te bottom tang probably wouldn't be chipped if there wasn't failure at the lockplates. There is "Only" one way this damage can happen and thats from firing the gun, Not shipping for darned sure. I know there are some excelent stockmakers on this board --- perhaps they have an opinion too.
This doesn't answer the question as to how the rib became loose ......
