I've never been a fan of shotguns in any Mass Effect game, until I tried the Pirahna.

I mainly use a Hornet SMG for my "general purpose" needs, and it's a great Assault Rifle substitute, but it's quite lacking versus big armored targets.  After hearing so many good things about this shotgun on these forums and elsewhere, I decided to give it a shot.  I used a stock Pirahna IV bought from a merchant, with no shotgun mods, and no points in the Shotgun passive.  I wanted a pure baseline test on the thing.  Even without a build designed to put out as much weapon damage as possible, this thing is a BEAST.  I can't wait to get enough research points to craft an even better version, and respec into a slightly more damaging build. 

I still use the Hornet as my "go-to" weapon, but this thing has now found a permanent slot in my weapon loadout.

I didn't want to try it on Insanity with it being just a baseline test, so I recorded a short Hardcore gameplay vid.  I was rather surprised at how well it did.