No, they have no facilities to take possession of your weapon.
If you have a weapon in your vehicle when coming on base, alert the airmen at the gate and they will provide you with further direction. Do not go on base with a weapon without alertin Security Forces. You consent to any and all searches of your vehicle by going on base.
Lock it in a box under the seat. Or on your body, unless you plan on killing people. SF (MP's) have no reason to search your car unless its a random check. They hardly ever check your body, its against the law. But if you have a pistol in the glovebox and they search you, they may detain you until the local police come.
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