Can i downgrade from ios 6 to ios 5.1

Hi guys i am currently having ios 6.0 on my iPhone 4.0 . My last software version which was working on my iPhone was 5.1 and i didn't updated it to 5.1.1 , means that i directly updated it to iOS 6.0 .I have the SHSH blobs of 5.1 so i want to know if there is any possibility of downgrading my iPhone to iOS 5.1 ??