My main problem with the MOC is that Toa of Lightning were canonically not this exactly like this MOC. Next time stick to canon exactly and do not deviate from the norm. Enjoy the Galigulag.
Other than that, he is a good boy.
Jokes aside, I'm glad you gave her Kaukau instead of that terrible Ruru. She looks great and the railgun is top. Have you got a picture of the inner frame of the legs? I'm curious how you attached those knees.