how to fix aim down sights when the weapon has an animation?

I followed this tutorial https://youtu.be/5uCbkv1tNvA?list=FLLkDJ3YftbeQwHP69UV8arw&t=152

and this is the result blueprint:


It works fine when I aim and shoot, but if I shoot first then aim, the arms get in a weird position, I think is because the shooting has an animation. Video:

I’m using just one camera. Is there way to fix this or should I look into other ways of aiming?