Question Blender - Bones shrinking in Pose Mode.

Hey guys. I haven't worked on 3d models in years. I decided to take a crack at it again and ran into some trouble. Whenever I rotate the arm, the bones are shrinking ! I don't know how to resolve this. I've been looking on google for hours. It's really getting in the way of progress. As you can see, the weight paint is distributed evenly so I don't understand the issue. Perhaps one of you more familiar with Blender can lend a hand ? *Preserve Volume is checked on as well.*

 

As fate would have it, I found the answer less than an hour after posting. I'm going to leave this thread up though, because I found the answer in a thread made back in 2013.

Basically, all you do is make sure your armature is scaled 1, 1, 1 in the x,y,z axis. Unparent the armature from the mesh first, then reapply after fixing scale.

Hope this helps someone in the future !