Hi i'm in megatown and trying to get a crippling injury but every time i jump of the ledge in front of the store i die same with the church. can any one help, mines and grenades don't do enough damage to brake a limb.

I take off my armor, stand on a mine and shoot it. If that doesn't work, you can try bouncing a grenade off a wall or jump off something a little lower than the ledge.