Aim offset keep both hands on gun

I’m using the starter pack aim offset with a rifle.

When the player looks up, the left hand moves further away from the gun before finally rebounding at the end of the aim offset back to where it should be.

Most people recommend an IK solution to glue the hand to the gun. However, I would prefer to solve this with animations. How can I keep my animations in my aim offset consistent so when the player is looking up, the hands are in the same place on the gun, without using IK?

(I prefer to avoid IK because, what if I have issues with a reload montage. When the player looks up, his left hand could be offset in the same way, causing it to not reload shotgun shells in the proper location. This is speculative, have not tested.)