How does a player with the hunting rifle in Left 4 Dead avoid getting overwhelmed?

Solution 1:

I only ever used the Hunting Rifle when playing the original Left 4 Dead, because it was so efficient at killing a huge number of zombies at long range.

If you get surrounded, crouch and melee zombies away, switching to your pistol to take them out as quickly as you can. The reason you crouch is so that when allies spray fire into the group, it only hits the zombies and doesn't hit you.

Ideally, however, you shouldn't get surrounded. Boomers are loud enough that you should be able to identify their location and snipe them before they bile you. There are clear audio clues to when there is about to be a big rush of zombies. Remember that the zombies always spawn some distance away and must rush towards you, and often clump together while they are doing so. Take advantage of the fact that your Hunting Rifle bullets pierce through the zombies and each one can kill multiple zombies.

When there's an especially narrow choke, you can kill an entire horde of zombies with just three or four well-placed shots. Your best defense is pre-emptively killing the zombies before they can surround you.

Solution 2:

One thing no one mentioned is that rifle bullets go through zombies, and headshots are one-hit kills, even on expert, so if you are in a corner (not completely surrounded), it's actually better to stand up and aim for their heads - you will take out an entire line of zombies with every shot.

By swinging left-and-right like this, shooting rapidly and meleeing every one or two shots, I've managed to fight off entire hoards of zombies on expert without taking damage.