I had a jerky / jumpy animation after making a bunch of changes to my game and it was driving me nuts. I couldn't seem to figure out why the animation would jerk forward then backward every so often. I had randomized the speed of several things making it even harder to figure out when it was happening.
So, I went back to the basics. I turned everything down to a more 'normal' animation speed and began to see that the jerking happened at frame 0 of my animation. I looked at everything I had changed and finally figure out that my Origin point was on the right side (basically the head) of my bullet. When I reset it to the middle, the jerking went away.
The jerking makes sense when you think about it.
Just a heads up for anyone with jerky or jumpy animations on a bullet. I searched and did not see anything. Perhaps this will help someone down the line.