Mini-14 w/can and M203
Same feelings about the Mini that's already been expressed. But I can add:
My Mini is one my father bought on my advice just prior to the '94 Assault Weapon ban. He was always unhappy with the accuracy, so I bought it from him instead of letting a pre-ban leave the family.
Very handy (especially with the Butler Creek folding stock). Didn't care for a vertical foregrip on it, which for some reason seems to be the rage on everything else these days...
Very reliable, of course.
I cut back the barrel on mine (front sight slips over a turned-down portion of the barrel and is pinned across a groove in top of the barrel). Then threaded the new muzzle.
I'm told that unscrewing the barrel on stainless Mini-14's tends to crack the investment-cast receiver
With a decent .223 can, I get an uncomfortable amount of blowback from the breech, something I don't notice with the same can on my AR-style guns. After all, the Mini's breech is pretty much wide open on top.
I also adapted an M203 40mm GL to it, since I didn't have an AR at the time. Used quick-detach ball-lock pins to mount it to a recess I cut under the forearm, with a barrel clamp/front sight assembly I made up (this was after I threaded the muzzle). Worked fine.
Ugly but handy and reliable.
I even dug up a coupla old pics, in case anybody was wondering what this monstosity looked like: