use Gun to control arm IK handles?

I have a character with both hands on a gun. The character already has IK handles on the arms.
I put a gun model in his hands.
I would like the gun model to be the control for both IK handles

If I use a “Child Of” bone constraint, I need a MAINTAIN OFFSET checkbox because I like my pose and the hands are properly placed already…

any help would be greatly appreciated!

NVMD!!! I realized I had forgotten to Apply Location, Rotation, and Scale to the Gun Mesh. Sorry for the dumb question… maybe this can help someone else out.