Downgrade iphone 4 to ios 6.1.2

[purplecat6660]

Is it possible to downgrade my iPhone 4 back to iOS 6.1.2 before jail breaking it?

I'm wanting to perform an untethered break however this doesn't seem to be available for iOS 6.1.3

Please confirm if this is correct?

Thanks

 

[willerz2]

It's possible assuming you have valid iOS 6.1.2 SHSH blobs and APTickets specifically for your device saved when 6.1.2 was signing