system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how can you survive having your leg blown off, but if you get shot in the leg cutting the main artery you die within minutes?

Just catched Band of Brothers on the TV, a dude named Hoob accidentally shot himself in the leg and cut his main artery and died within minutes. 

And then there were these 2 other dudes that had their right legs blown off and survived.

This happened in real life too.
gpt
When the muscles get torn free, they ball up and contract really tightly in what remains of the limb, tightly enough that they can stem the blood all on their own.  When you get shot or stabbed, the muscle's still attached at the other end, so it can't ball up or tense up enough to block the blood flow.