A selfkill isn't necessary, just press x (or whatever your prone button is) whilst the bug is occuring, to return to normal.
Sometimes, when I play with spas, my ammo reaches down to 1, and whenever I backflip, the crouch bug occurs. It's very strange as it has only occured a few times, and whenever this happens and I reload, the bug will stop occuring. Anyone else experienced this before? No, we are not talking about modded weapons here.