Overlapping action - Hammer

This is an example to show how the overlapping action works. An overlapping action basically means that not every single thing moves at the same time, and that parts that have joints will follow the main object but will react a little bit after the movement of the object.
Here is a hammer as the main object that has a metal spring on the top which reacts as the hammer hits the ground. It could be seen how the metal spring continues to move after the hammer stops, but because it is a spring I have put more movement to show this, this is the follow trough.
I have also wanted to show that the hammer is heavy so when it hits the ground it bounces a little bit.
There's one thing that I think it can be improved: the hammer has 4 swings but one of them which is the first looks like it's slower than the others and this gives the impression of accelerating (it is difficult to see where it's the start because it's a .gif image but it can be seen a little acceleration).