Problem with a legacy animation made in unity

Hi everyone, i have a very serious problem in my game that i can't solve, i have imported a character that i've made and rigged, i can see the various bones and stuff in the character's gameobject hierarchy, the problem is this: i have made some animation for that character with the integrated animation making system, frame by frame, i know this is not the best way to do it, but in this case i need to simplify the game's structure as much as i can. This character holds a pistol, which is child of the character model, in the aim animation for that gun i basically animate the whole character and i place the gun in the hand of the character, then i use CharacterModelGameObject.GetComponent().Play(AimAnim) (for example) so i can play the animation on the character. The prolem is that the animation gets played but the pistol is in the wrong position, slightly off to the right and it collides with the hand of the character.

I really don't know how to solve this issue, i hope you can help me out because i am really struggling solving this problem!