I have a fully rigged model, and everything works fine, but when I go to rotate a bone, it scales the limb down as it rotates, and scales the limb back to normal size as I rotate it back… If you need further explanation just let me know. Any help is appreciated… Thanks.
You need to check your weight painting. You probably have two bones that are sharing the verts at 50/50 weight. As you rotate one of the bones close to 180 degrees, you bones will shrink. You need to ensure that parts of your mesh that should be controlled by 1 bone have a weight of “1.0” for that bone and a weight of “0” for all the others.
Scale is off. Apply [Ctrl][A] scale to Armature and object being controlled.
It’s weight painted perfectly, I double checked. And I went into object mode and applied scale to the armature and the object seperately. Still shrinks limbs when rotated. Don’t give up on me though lol, I’ved searched the entire internet and nobody’s been able to help me.
Weight painting’s all perfect, and I applied scale to the armature and th eobject. Please dont give up on me though Lol, no one seems to be able to help me 
Here’s what happens when i rotate something
Attachments
The best way to get more help will be to post your .blend file. From your screen shots it still looks like a normal weight blending issue.
You have a weight painting problem. The root bone is painted at weight “1.0” for the entire model. This is what is causing the weird scaling issue and it will happen for any bone that you try to rotate.
The solution is to set the root bone to weight “0.0”. When you move the root bone it will move all the other bones in the armature and that makes the entire model move.
If you are not careful with the weights in Blender you can really shoot yourself in the foot. You probably assumed that Blender enforces that each vertex only adds up to “1.0”. It only does that if you have the “Auto-normalize” checkbox enabled while you are weight painting.
Oh my god. Thank you so much! I really do appreciate it. And now i’ve learned something haha. Thank you so much, really. 