Sprite h-align between two animation with different sprite size

Hi. I have an Idle animation composed of 16x24 sprites and a Punch animation composed of 21x24 sprites becaus the arm is stretched out.

The left side of the sprites between two animation, are perfecly aligned so the Head of Player start 6pixel from the left edge in both sprites (idle and punch).

Unfortunally, when the animation go from Idle -> Punch, che sprite on screen make a light move to the left so the head is not aligned from the previous position.

Is there any way to force an edge so sprites will adapts automatically from a specific point o view?

Thanks.