Bullets may go through people without harming the critical bits. It's relatively frequent.
Many wounds are survivable... Perhaps most. Still, some are full-blown crippling and others, perhaps most, cause moderate disabilities.
If shrapnel shreds a big enough part of a muscle, you're gonna face long and frustrating recovery training to get your strength back, and there's no guarantee you'll regain it completely.
You exist because we allow it and you will end because we demand it.