Might as well add the very basic spriting I did for akimbo super shotguns for a mod I released recently. Still kinda crude but it's a start at least.
The flash state shown is just a tiny taste of the utter madness that was spriting up flash states. See, I'd went with the idea of the shotguns letting you fire one barrel at a time by default, with altfire firing both barrels. Simple enough, just have primary fire fire off the left barrel, then the right barrel if it's your second shot before reloading, and altfire is the same old flash sprites the super shotgun uses normally.
So having two shotguns makes it more complicated. Four barrels, so that's four separate muzzle flash positions, and two sprites for each. Then, of course, you can still touch off two barrels at a time for the altfire. It can be done from 2 chambers loaded up to all 4 loaded, so that's three more pairs of flash sprites based on which specific barrels are used (the two on the left shotgun, one from each, or the two on the right depending on chambers available).
I think I have a grand total of 20 flash state sprites, hence why I've yet to dabble with adding distinct muzzle flash effects for incendiary or plasma shells since each will need 20 more that I'd have to edit together AND tweak until I have the offsets exactly right. XD