Don't fix the sprite, make the sprite, as in get GraphicsgGale and draw a new cannon, not some doors stuck together and recolored.

Good shape, but colored uglier than a two-tone... Thing that's... ugly. Wait, it is.

I see you respritin', I'm hatin', trolling just tryna catchu respriting dooooors.

- Seriously though, work on the resprite stuff. Making a turret is a commendable task so you get kudos for effort.

Update
re-sprited the base from scratch!

The attachments failed.

yeah, i was still editing it. here re-dl, it should work now.
tomorrow ill re-scale the gun, and edit some code. im starting to want a realistic railgun (smaller flamings shells of death )

Actually, real railguns don't have any effects in the air, only from the barrel (When they break the sound barrier they create a shockwave) and when they impact.

Unless you're loading them with depleted uranium or something else that can burn when heated.

shading.. shaaading.. SHADING DAMN IT!!! Do you actually know what it means? Stop remodeling the thing and SHADE IT!

The new shape is better than the old sprite (more slender), but it still lacks shading. We are talking about the effects the sun (or any source of light for that matter) has on the different parts of the sprite, to give it more dimension and depth. If you need help, look at sprites like the Dummy Dreadnought, coalition helmet, and some weapons to get an idea on how it should look after shading.

Much better looking. Good work.

Make sure you add a thunder crack for the firing sound.

And a capacitor charge noise for the reload after every shot!

One of my final science projects last year was constructing a gauss gun to fire BBs 20ft, made out of some camera circuits, and about 8 large capacitors. The long, loud, and eventually high-pitched whine was probably the best part about it, and totally made up for it melting the coils after too many runs.

Old and low-quality transformer noise, probably. Capacitors are silent, as far as I know.

Cheap electrolytic capacitors do this too, and it's not a great sign.
But yes, imperfect transformers produce plenty of noise at high voltages, and this just reinforces my desire to have this gun make noise.
Also, for the gun to auto-destroy when dropped, for the turret to stay pinned better, and for the shell to not be a giant bullet.
Railguns don't fire giant flat things, they would overheat too much from the resistance to acceleration.
More like this http://en.wikipedia.org/wiki/File:German_railgun_Bild_4.gif.

Also, when you are talking about that kind of scale, the gun is going to make tons of heat. Some serious heat venting is in order.
Emitters on the barrel triggered to release some glowyness would look cool, maybe some vapor as well.
Just throwing some ideas out there.