A couple of different themes are mingled here.
It is true that there is no net advantage to most criminal defendants in talking to the police, even where the police threaten to or actually do abuse your person or property.
The OP brings up a different issue though.
This was brought home by a poster that happily rattled off his ammunition inventory to a 'friendly' LEO pumping him for information.
Rattling off your extensive ammunition inventory isn't normal. Bragging about your own personal armory will be construed by non-gun people, of which many policemen are, as a sign of an imbalance that combined with your now obvious ability to cause harm logically merits some investigation.