The card for these weapons don't state to discard the target lock, or focus. Only that you have to have them.

In a recent game that argument came up, my opponent was saying the target lock still got discarded, since that's the way ordinance works.

Which is correct? Do you keep the target lock after firing these? In the case of the Proton Rockets do you even need a target lock?

Thanks in advance.

Do what the card says, and don't do what it doesn't say.

With these missiles, you don't have to spend your Target Lock / Focus, simply because most ordnance says to.

In the case of Homing Missiles and Ion Pulse Missiles you must have a target lock on the defender, but as the card says, you only discard the card. Which means you are able to use the target lock for any rerolls that may be needed.

With Proton Rockets, you just need to have a focus token on your ship, so when you fire them, you discard the card, but keep the focus token which you can use to modify the dice roll if need be.

As DraconPyrothayan says "Do what the card says, and don't do what it doesn't say."