So we are all waiting for the next patch with hopes that the S.D.M.G will finally be a regular weapon, and I thought perhaps we could push it one step further.
I have no idea what sort of stats would be best for this weapon, so I'll just go over the concept.
Here we have a rapid fire weapon similar to the chaingun, spraying bullets at a high rate, but the special feature of the O.M.G. that sets it apart from other ranged weapons is the large muzzle flare that it shoots in tandem with the bullets. This allows it to cause more damage when up close to targets by combining muzzle flare damage with the bullets it fires. Think of it as a chaingun with a small flamethrower effect that doesn't use gel.
Another feature is the animated barrel that adds character to the gun.
This weapon should be very high fire rate, high damage-per-minute, and very hungry for ammo. This late in the game, a player should hopefully be able to afford the huge piles of ammo that this gun will consume. This isn't a gun design for efficiency or subtlety, but for gross display of power. It has a 50% chance to consume MORE ammo, but it's destructive potential should make it a sublime choice for moon events and boss fights if you can feed it.
Here's a sprite concept. The native particle effects in Terraria could do a much more dramatic muzzle flare than this example.
Here's an example with no muzzle flare.
This big fat chain gun can't wait to eat up all your ammunition and blow away all the competition.
Old TO thread here; http://www.terrariaonline.com/threads/megawhale.142199/