Mecanim animation not working correctly after separating from original fbx

This has to be the fifth problem I've encountered by now with mecanim. I haven't even been able to start working on my project because I've been spending my entire time searching solutions.

Basically, I made a gun without animation and exported it into an fbx. Then I made an animation for the gun, and exported that into a separate fbx. Since the @ naming convention isn't working for me, I had to resort to importing each model, expanding the one with the animation and copying the animation. Then I delete the model and I'm left with only the model without the animation, and the animation file I extracted from the one with the animation.

The thing is, the animation doesn't work correctly after splitting it. I kept testing different things out and it seems that If I keep the model with the animation, and use the animation on the model without the animation, it works perfectly. But If I copy the animation and delete the original model, whenever I use the animation on the gun without the animation it doesn't look right.

Here's a video of what it looks like: http://www.youtube.com/watch?v=p1c_YY0AGrI&feature=youtu.be To the right is what happens when I delete the original model and only keep the animation, then apply it to the model without any animations. To the left is what It's supposed to look like. This problem doesn't happen if use legacy animations.

I watched the mecanim tutorial and really really wanted to start using mecanim, but it seems I keep running into a problem every 10 minutes.