I have always learned that muzzle must point downwards allways.
Only if you are taking aim or searching for targets the muzzle is up.
The reason i'm asking is because in a Norwegian forum they have this tread, named Muzzle or Down, one of the longest treads on that forum..
Apparently they don't have any SOP's on the subject.

" sometimes i patrol the muzzle up sometimes down"...
" if there is snow i have the muzzle up"
" see, the US seals also do it(a video from a junglepatrol)."

And this is conscripts most of them.
Anyone..??