Hello,
What you can do for your projectile blueprint is add a float variable and check the box for Expose on Spawn (it will also need to be Editable), in this example I’ll call it Projectile Speed. In your projectile blueprint’s construction script, you can use a reference to your Projectile Movement component to call and set your Initial Speed using the Projectile Speed float you just created:
Now, in your Character blueprint (or wherever you are spawning this projectile) when you spawn your projectile, your Projectile Speed float will be available for you to pass in a value, which it will automatically set when created (spawned):
Hope this helps you out!
-Steve