If tu are surrounded por alot of zombies tu won't have time to reload the gun over and over again. And depending on the el espacio tu won't have room to shoot at them. But then again tu may have some el espacio so it depends. And even if tu do get some bullets off. Alot of times zombies react to sound so tu are definitely increasing your chances of being killed por them.
It's best tu find a way to escape because no matter what if tu stay there faced with the current situation tu will most definitely die. o if tu have a weapon designed for close-corner fighting tu may survive that is if tu can keep up with your opponent and even still that isn't a guarantee.
If por some chance tu have grenades. That could potentially help considering it will make a path and may draw the zombies away from you. Plus destroy any zombie that was in the direction of the grenade explosion and then if would be a good idea to make a mad dash for the exit.