The cent may have started out a little heavy.
does your scale measure out to 2 decimal points? (eg - 3.11g)
if not your coin could weigh as little as 3.05 and is rounding up....
But Seeing how your CENT has no reverse rims, it has been reduced manually (sanded).
There is no sign of the 'proto rim either. The proto rim is formed during the up-setting phase that turns a blank into a planchet.