CREATE TABLE table_23429 ("Colt model no." TEXT, "Military designation" TEXT, "Barrel Length" TEXT, "Barrel" TEXT, "Handguard type" TEXT, "Buttstock type" TEXT, "Pistol grip type" TEXT, "Lower receiver type" TEXT, "Upper receiver type" TEXT, "Rear sight type" TEXT, "Front sight type" TEXT, "Muzzle device" TEXT, "Forward assist?" TEXT, "Case deflector?" TEXT, "Bayonet lug?" TEXT, "Trigger pack" TEXT)

How many case deflectors are there for the Colt 646?
SELECT COUNT("Case deflector?") FROM table_23429 WHERE "Colt model no." = '646'
SELECT COUNT("Case deflector?") FROM "table_23429" WHERE "Colt model no." = '646'