It split well back into the chamber! Someone is probably missing a hand if they're still alive after that. The barrel looks like it's marked 30/06 and 308 NORM. .308 Norma case length is 0.065" longer than .30-06, and without looking at drawings to see where the shoulder is, this is what I think. If it was a .30-06 re-chambered to .308 Norma, then someone shot .30-06 ammo in it, it would have excessive headspace, and if not it would still have lots of room all around the body of the case. The .300 H&H magnum size bolt could possibly feed .30-06, I don't know, but if it did, the bullet and neck of the cartridge would hold it in the chamber. And .30-06 SAAMI maximum pressure is even higher than .308 Norma magnum, which wouldn't help the situation.