As I said in the original running out ammo post – you have used up all your shotgun slugs, and all you have left is birdshot. But…let’s say you don’t have the ability to melt and make slugs as proposed in the first post.
You still might be able to survive (for at least a little while longer).
Take your birdshot slug and carefully cut the shell in a circular pattern, but leave an overlapping section to hold it together.
It might just let you take down a few more walkers and survive just a bit longer.