Here is translation-summery I did on different thread. Seems like a doubly stupid "accident".
"Basically, that article in Jakt and Jägare (Hunting and Hunter) about blown rolling block reports that a rolling block in 12,7X44R (basically 50-70 USGovt) made in 1872 and in dubious condition ruptured badly, with peice of breach block impacting shooter and causing severe skull injuries. The 24-year old shooter died 2 days later. The ammo was old, corroded, diverse and included some 50 Express rounds. The gun had been test fired previously. Unknown what ammo was used in test shooting or in shot that ruptered gun."