Mecanim Blend Tree: transition not smooth

Hi, I have an issue regarding the blend tree I have created.

The blend tree I created consists of a running animation and a “Shoot while running” animation for a humanoid character I modeled.

My intention is when I click the “t” button while holding down the right button(running animation), the character should transit from the running animation to the “Shoot while running” animation.

However, the solution I came up with was using the script to change the float value.
Here is an example of my code:

if (currentBaseState.nameHash == locoState) //Blend Tree

			anim.SetFloat ("Running" , 1);   
		else if (!Input.GetKey(KeyCode.T))
			anim.SetFloat ("Running" , 0);

Everything worked fine but the transition wasn’t smooth, in fact, there is no real “blending” of the animations. I understand this may not be the correct workflow for the blend tree and thus I would like to understand if there are any other way I could work around it?

For real blending you need to add an upper body only animation for shooting and put it in a higher layer in the state machine. Make sure its additive, then you blend by adjusting the weight.
You can also create a bodymask to select particular bones to use/ignore.