Was it "supposed to be" or was that just what you asked for? Some places tell you they'll send whatever they have that's closest to what you ask for, but they often let you specify if you ONLY want exactly what you ask for.
Depending on the nature of the seller, why not contact him/her and ask them why you didn't get what you asked for (politely, of course) and if they can get you that pin or if you have any other options.
If you're that uncomfortable with a 5" pin, don't be in such a rush to drill it. With the Inferno's core and surface, there are probably many possibilities.
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"Just because you can do something does not mean you should do it."