Vall, about 20 years ago, I worked for a firm that made custom bullets for African-type rifles. We used an Eddystone P-14 fitted with a 50BMG barrel cut off at the breech and rechambered for .510 Wells as a test rifle. The rifle had an issue P-14 stock minus the military hardware and fitted with a thick recoil pad. The Wells cartridge is a blown-out 460 Weatherby. I shot it many hundreds of times at velocities in the 2200-2450 fps range doing quality control work. The loads burned about 100 grains of 4350. Never any problems and it was quite accurate with the issue rear sight and a front post mounted on a ramp. IIRC, barrel length was about 45 inches.
At the same time, we used a Cogswell & Harrison Magnum Mauser in .404 Jeffery as another test rifle. With heavy loads, the stock came completely apart at the pistol grip. Receiver struck me on the right cheek and ear as the front part of the rifle whizzed over my shoulder. Left me with bruises but that's all. But for my grip on the forend with my left hand, my injuries might have been worse. That was a failure of the wood in the stock, not of the action.
I saw the Eddystones with the oddly shaped receivers about the same time. They had a low spot on the left wall just behind the receiver ring. Each low spot was slightly different in shape. A low spot in that location had nothing to do with clip loading. I think it was poor quality control.
