You can fish and hunt in Missouri without a permit if you are an honorably discharged disabled veteran or a qualifying service member. Trapping is not included, and you still need permits for deer, turkey and migratory birds as well as any conservation stamps.
There is nothing to apply for. Carry your certified statement of eligibility from the VA, or your orders showing your assignment, whenever you hunt or fish.
A certified statement of eligibility from the VA, or orders showing your assignment to a Warrior Transition Brigade, Warrior Transition Unit or military medical center.