How do I move an item on its axis when its rotated? I'm not totally sure how to word this so I'll do my best.
Im trying to animate a gun, and when I want the stock to move while the character is shooting the gun, I wanna move the stock.
Basically, I wanna move the stock with the rotation instead of it just going on the regular axis.
I'm not good at explaining this, if I used the words in the wrong way then I'm sorry.

Basically, what I'm trying to explain is when I rotate something and then move it, its on the normal grid axis instead of what its facing when its rotated.

The green line from this brick isn't facing the same way as the brick.
I think what you're trying to describe is moving along the local axis. Assuming you haven't applied the rotation of the model, you should be able to press g to move the model and then the axis you want to move on TWICE. When you press the axis key twice it goes in that local axis rather than in the world view.
I can go ahead and include some images if you need! Let me know if this helps you out.