vertices not scalng with bone in blendswap rig

how do I set it up so scaling down bones shrinks meshes arms as well?

the scale is a bit off

Most probably, you are scaling non-deforming bones. This armature has several layers, and it is possible that the deforming bones are on another layer.

Could you link the page the file is on? It would be easier to debug if I had a file to look at. Some rigs are not set up for scaling and may have some channels locked to prevent it.

As Ovnuniarchos stated, you have one bone layer that I can see not visible/enabled. That is most likely the deformation bone layer. That may or may not help in this case. It will mainly depend on your IK/FK rigging and if the rigger made it possible to scale the legs/arms/torso, etc.

Good luck!

I already deleted the fk arm bones…

You could scale the MCH-upper_arm.L bone on the local y axis and get what you need. (Hidden on the last layer.)

This is kind of a hacky way to do it. This rig is not set up for this type of scaling. Scaling that bone will mess up the location of your IK target a bit depending on how much you scale it.

Personally, I would re-rig the whole thing, but that’s just me.

Good luck!

Thanks, got it working, Had that layer marked as protected