Well it's not really good because you probably used a brush with a blurry outstrike andalso blurred the gradients.
I made a quick example on ps, with hard round basic brush.
I'd sugest to work with a palette of 4 colors like i show on the pic and make solid gradients to start.
Then you just need too zoom and add more gradient tones of greys.
The more tones of greys you add better will be the gradient...
also don't forget the little lines bright lines on the sides of the form because that's how metal reflections are, there's always a little return of light on the rounds.
You can use grey gradients like this but it's not realistic at all because a real good gradien has more colors, not only gray, depending on the ambience of the scene, per example for this one i'd add some blue, as i did on the last exmaple at right of the pic.
I should have made blue/grey gradients when i was making my gradient but as i forgot i just added another layer with a blue/grey gradient and set the layer to color doge mode with 30% of fill to give to the gradient some blue ambience.
You cannot really notice it but on a scene that would have a blue color ambience that would make your object with blue gradients blend better and give it a different feeling.
Hope that helps
