Rod, as often is the case, super-precise measuring of the object's weight could shed light on whether it is an Original or not. These were all manufactured at Mr. Parrott's Cold Springs Foundry, so the metal alloy used in the Originals should be consistent. Check with other collectors to get super-precise weights, then compare their data with yours.
I can't see the "mushrooming" you report at the base well enough to form an opinion about whether it was caused by explosion of the shell or merely the fuzeplug got dropped onto that end. But, I believe the bent flange (at this fuzeplug's top) is too "extensive" to have been caused by anything less than explosion-related impact damage.
Regards,
Pete
