Reference without Transform

Hi everyone! Im currently working on a 2D game and have the problem, that I cant reference the bullet prefab.
The gun first has to be picked up by a player, then, when the gun is picked up, it gets the “gunScript”. (already done!)
Therefore I dont think that it is possible to use Transform and drag the prefab into the script.
I already did some research and tried a couple of methods, but without success.
Would appreciate any help!

Can’t it have the gun script from the very beginning?

If not it could at least have a script that only contains a reference to the bullet prefab.