Retarget Animations for Non-Traditional (Weapons) Skeletons?

Hi all!

I am in the process of retargeting some gun animations to use a different skeleton.

I have hooked up some bone chains in retargeter but I am having trouble with bone translations. Specifically, if I use “Absolute” translation mode for bone such like Bolt or Magazine, then it comes with an initial offset (shown in pic) since the skeleton size is different. If I use “Stretch Bone Length Uniformly” mode then the bones look like are in the right place, but won’t translate during animation. I am not sure if I should adjust the retarget pose, but it won’t allow me to move the bones either (only rotation). Just wondering if anyone has idea on how to properly do this?

Any guidance and help would be appreciated!