They don't find weapons because the criminal behavior has changed. They know they stand a good chance of being stopped, so they don't carry their guns and lives are saved.
Mr. Slocum, I don't know where you live, but I am a lifelong Bronx resident. NYC used to have more than 2,000 murders a year and now it is down to 400. Most of those deaths were and are minorities.
"Stop and Frisk" saves lives, period. And, most of the lives saved are minorities.