Pair of them, actually:
Don't shoot reloads put together by someone else unless you know and trust their work.
And if you pull the trigger and don't get a proper 'boom', stop right there and make sure everything is clear. Or else.
#7 managed to blow both the stuck bullet from the squib and itself out, bulging the barrel and splitting it lengthwise in two places.
Better look at one split
The wonders of modern steel and heat-treatment: not a scratch or other mark on the frame or slide.