Is this a different blueprint that has an actor object reference?
Take a look at this document:
https://docs.unrealengine.com/en-us/Gameplay/HowTo/SpawnAndDestroyActors/Blueprints
If you look at step 3, you notice they are setting the actor class type. If you have the variable mentioned in your previous post you can pass it along here to tell the node which gun to spawn.