A young adult(19) hunting deer for the first time was given a 7mm rem. magnum to use, as he had no rifle of his own. During the hunt he bumped the scope and took it to a nearby gravel pit to test the accuracy. At the gravel pit he loaded three rounds into the magazine.( M77 ruger 7mm mag) closed the bolt and upon pulling the trigger the rifle failed to fire. He opened the bolt and the round extracted. He again closed the bolt and tried to fire and nothing happened. Thinking something was wrong with the rifle he reinserted the misfired rounds back into the magazine well. On the 4th attempt the rifle discharged (forward and backwards) The bolt flew back cutting the shooters thumb, the trap door(magazine floorplate) blew open and bent, and the stock split. The shooter received powder burns to his face and numerous small cuts and abrasions.
The cartridges he mistakenly took with him were clearly marked 7mm-08. Not knowing one 7mm from another, thinking 7mm was 7mm was a big factor in this incident. The family member assumed he knew there is a difference in these caliber’s.
The attached pictures show the cartridges from this incident. All are factory loads . The 7mm=08 round that is next to the damaged one has a dimpled primer from the attempted firing. The bolt captured this cartridge and carried it into and out of the chamber.
Upon examination of this incident it was found that the bolt(with claw style extractor) will pick up the incorrect cartridge and hold it to the bolt face during firing. Being so loose in the chamber allowed gasses to travel back and with the loose case pushed to one side, rotate the bolt open.
Undoubtedly many incidents similar to this occur, but unless a serious injury of death results the incident is unreported.