I'm looking for a fic where Dean and Sam are on a case in the middle of the woods and stumble across a group of armed men who (I think) hunt humans for sport.

They shoot Dean because they want to test the brothers' loyalties(?) and see if Sam abandons Dean to save his own skin, but the brothers end up taking the group down one by one, using survival tricks John taught them.

The fic was gen and, I think, an older one set in pre-season 5, but I can't be sure.

Edit: Found! To The End by K Hanna Korossy