I do feel like the dark blue color is not quite good and you should probably change most of it to metal and probably change the color to black too. which gives that realistic look to the gun. But yea if you want the smooth plastic material too go for it!! Anyways keep it up!
Depends of the game’s style, you should make it a bit brighter because making it all black will just hide some details that you may want to show off, also about materials, I recommend using SmoothPlastic with different colors and reflection set to 0.1, that faded reflection with the shine of smooth plastic really makes it look nice
OR since this kinda looks like a gun from Halo CE make it metal and gray