It's already on a form 4 in Ohio... that's key.
For and out of state transfer, the seller will need to transfer their silencer to their in state)FFL/SOT with a Form 4 and pay the $200 tax stamp. The FFL/SOT would then transfer the silencer to an FFL/SOT in the buyer’s state using a Form 3 (this form does not require a fee). After that, the buyer’s FFL/SOT would transfer the silencer to the buyer, using a Form 4 and paying the $200 tax stamp.