How to drive blend animation via blueprint

I’m trying to control a blend animation with my character’s blueprint. Essentially, this is what I’m doing:
I’m using a trace line to see if the player’s gun clips through stuff infront of us. This spits out a float. For my mesh (arms holding the gun) I have a 1D blendspace that goes from ‘gun out’ to ‘gun pulled back’ so that it doesn’t clip.

Inside that mesh’s animation blueprint, I have this blend all set up, and I have a float to control the blend.

How do I get my float from my character blueprint to the animation blueprint to drive that blend? I’m getting somewhat proficient within blueprints, but when it comes to getting them to talk to one-another, I’m having a lot of problems. Why can’t I just use global variables like in other engines?

I don’t fully understand Casting. Perhaps I need to use casting somehow?

Ok, after chatting to some other Unreal folks, they said that yes, Casting is what I needed. For some reason I’ve had a really hard time wrapping my head around Casting, but I think I’ve got it now. If anyone has a better way of doing this, or if Casting isn’t my best option, let me know, but here is what I’ve got now.

Hi! Maybe you already know this, but anyway: “This diagram illustrates the flow and ownership of data for a typical animated character in Unreal…” Animation System Overview | Unreal Engine Documentation

You can see that data from CharacterBlueprint is moving to EventGraph and then to AnimGraph. In EventGraph you can Cast only once, store your pawn and update each variable each tick.

I hadn’t seen this page yet, thanks!