I'm trying to downgrade my iPhone 4S 6.1.3 to 6.1.2?

I tried changing to host server code but its still not working.
Is there any programs i could use to downgrade?
I've been working so hard trying to find a way to jailbreak my iPhone 4S 6.1.3.
I also used to TinyUmbrella to see of i had any shsh blobs and i did for 6.1.2 so i don't know why it isn't working?

You can't downgrade the iPhone 4S due to the A5 chip. You can't jailbreak 6.1.3 either.