I have found one and i sold it (silver rush counter) but the wiki says you can buy it from the silver rush which i cannot find and no matter how much times i refresh it can you help me?

Sorry but the Plasma Caster is unique, so I hope you have a save from before you sold it.

no it is not a unique weapon like the Q-35 or the YCS

It is, I've never seen another like it in the whole game.

They need to edit the wiki then cause i spent an hour of my life waiting and it never appeared in the sr's inventory

The Plasma Caster is not a unique weapon, however for it to show in the SR's inventory you need to be at least L21. In addition to that, said shop is one of those with restocking issues as Gloria's inventory tends to get 'stuck' and not refresh when it's supposed to.

I have managed to find one for sale in addition to the one on the counter, which was one of the times I did not loot the place blind after waiting out the entry scene. It's been reported that doing so hoses the shop, however there's no real way to prove it until they fix the buggy merchant containers and game-day reset issue (reverts to Sunday if you exit completely and start a new session).

Theres a bug that prevents the silver rush's inventory from scaling with player level. Plasma caster should be sold at SR late level. But the bug maintains the low level selection.

Lol. You stole it, sold it to them, and then waited for a new one to appear? Switch to unarmed mate.

im maxed out at level 35