I recall reading somewhere of a trapdoor someone got, they tried shooting it, but had to "retire" it. Seems someone before had shot some kind of stupid overloads, they actually stretched the chamber into an oval shape. But the action held whatever load they were using.
The "play" in the hinge on the trapdoor action lets the breechblock "back up" against the rear of the receiver, that's what takes the back thrust from firing, not the hinge.
Somewhat along the same lines, I once looked at a Krag in a gunshop, that was chambered for a 30-06.(or maybe was meant to be 30-03) It didn't appear to be altered, and the bolt face was made to fit the rimless case. It wasn't for sale, but the owner had left it with the gunsmith to try and find out any information on it. He wasn't having any luck, and this was pre-internet. Maybe something they used to develop the new cartridge? Or maybe they considered the idea of re-chambering Krags and keeping them in service longer?