"tec" asked about establishing the age of the manuscripts, and fragments, that we do have. Carbon dating is one method, paleography is another.
The alphabets, scribal notes, language usage etc all change very quickly, as in the change from Shakesperean English to today's. So dating is a fairly exact science, always with the caveat that a few years either way must be allowed.
So, we know for sure, that all we have are copies of copies of more copies that were probably translations in many cases.
Even if we had the original autographs, we would still have to ask when was the writer at work, and more importantly, why was he at work ? What was his agenda ?
So it is very silly to argue about "every jot and tittle", it is very silly to say "Jesus said..." or similar, and it is downright criminal to build a doctrine such as the WT's on refusing the life saving use of blood, on such flimsy, unverifiable sources.