Hey, I recently purchased a synthetic Remington 870 Express 16-gauge shotgun from a pawn shop. On the gun, there is a safety mechanism that requires a key to unlock. I believe the key is known as an ISS key (internal safety something). To operate this gun, I'm going to need to purchase this key. Does anyone know if all of the ISS keys are the same for Remington shotguns? Thank you for any responses.