My buddy blew up his Whitworth Mauser action custom 7mm Weatherby magnum and it looked a lot like that. The Action over the barrel threads pealed back, the barrel flew forward about 3 ' and it broke the maple stock in multiple pieces. The bolt was bent inside the action. It didn't break the scope in half but did bend it. the rear portion of the case disappeared and the part in the barrel is welded tight. He was shooting ammo he had loaded perhaps 10 yrs before. It was hot. He had been blowing primers for some time without noticing it. (looking at the half empty box of ammo with primers blown and missing. He had been hunting with these rounds for years. When he went to check zero the first shot from a clean barrel blew the rifle apart.
In pulling down the rest of the ammo he had a very difficult time with the impact puller. The bullets and cases inside the neck were covered with vertigris, that green corrosion residue. He weighed the powder and it weighed what he loaded (it was supposed to be a max load of H-4831 from an old manual, but had been fired for many years without incident leading up to this disaster.) He tossed the powder before I could get a look at it. He had both H-4831 and IMR 4831 on hand and isn't sure he didn't mistake one for the other.
The cases with the blown primers had been used for hunting and fired to check zero and take game. Yes he is a fool. The person who built the rifle for him developed a load and Dave just copied it when he needed more ammo.
Dave believed it was the old ammo with corrosion inside that caused the destruction, but isn't sure that he might not have mistakenly used IMR 4831 for H-4831. Whatever happened was a massive overload. HIs action was bent beyond recognition with the metal over the barrel threads pealed back like Popeye's spinach can lid.
Dave's eyeglasses were etched and pitted (I assume from gas and bits of the vaporized brass) and he had a small 1/4" shallow cut on his cheek. His trigger hand was sore (said it kicked like a mule). Otherwise he was uninjured.
The barrel looks fine, like it could be reused if you could get the front half of the case out of the chamber, if there was an obstruction it went out the bore cleanly.
Dave is contemplating only using factory ammo from now on. Probably a pretty good decision.