I had the same thought not long ago. It was based on the canister/rack idea in that you'd load up a can/rack and then they'd be pushed into a launch tube and logic gates would repeat some push lasers to force them out. I thought it'd look awesome but honestly I think unless the timing was perfect it'd be a little too slow, each drone would prolly be chewed up before the swarm was entirely done....Your cannister concept would probably work better on smaller ships than my drone rack tbh, considering that it would need less space.
I'm starting to think about a magazine fed skoomdrone launcher type thing (only one barrel to shoot multiple drones separately). It's just a concept in my head but I think that it could work :D
Then again if it shoots behind you... drones would take longer to get there, meh, it's a lot of logic gating to get that to function, maybe I'll make a giant tommy gun that does that or perhaps a shotgun style to launch em all at once? xP
Link to Canister DL...https://www.dropbox.com/s/cuva9fudjm809nm/TinCan Quad.sment?dl=0
(I know I can upload here, it's just faster to dropbox it before hand while I fiddle with descriptions and things :p)