Downgrade iPad 4 with stock iOS 7.1.2 to 6.1.3

Dec 22, 2014
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I purchased a iPad 4 that came with a stock 7.1.2 I want to downgrade it to 6.1.3 . I have jailbroken my 7.1.2 and it has become unstable . I cannot find any procedure or software to do it . If it is near impossible then can I just reinstall my 7.1.2 ? And what is the procedure to save the SHSH BLOBS to do it .