40% silver Kennedys frequently sell for a bit under spot. Home made silver bars typically sell for considerably under spot. Plus you have the added costs of recovering the silver, refining the silver, and proper waste disposal. A trip to the Gold Refining Forum should help you understand the processes of recovery of silver from the coins, and later refining that silver, should you decide to proceed.
If you decide to attempt to recover and refine silver from your coins, please stay away from YouTube for now. Far too many videos either leave out safety procedures that will keep you safe and alive, or their procedures are actually wrong. If you start with a forum that helps you learn to refine properly, you have far better chances of doing it right without severe complication or injury.
That being said, my advice is, if you want to sell, sell as is.