If that Mg42 owner has a half of a brain placing and microing MG42 not a single chance. It needs a third window switch to get near enough to take out the mg. It can keep those 2 sides down until Grens/pios come to mop that squad away.
If you've got half of a brain yourself, you can approach the MG outside of the firing arc but close to another side of the building so when the MG goes to set-up on the flanker's side, the flanker then can go a side the MG won't be able to shoot at while its setting up to where they were before and then nade it.
That was harder when Maxims and M2HBs set-up much faster in buildings, but now that is easily feasible against all single HMGs in a building.