Table: m16_specs
Columns: colt_model_no
military_designation
barrel_length
barrel
handguard_type
buttstock_type
pistol_grip_type
lower_receiver_type
upper_receiver_type
rear_sight_type
front_sight_type
muzzle_device
forward_assist
case_deflector
bayonet_lug
trigger_pack

Question: What is the trigger pack on the Colt 602 with the a1 rear sight type? 
SQL: SELECT "trigger_pack" FROM m16_specs WHERE "rear_sight_type" = 'A1' AND "colt_model_no" = '602'

Question: How many case deflectors are there for the Colt 646? 
SQL: SELECT COUNT("case_deflector") FROM m16_specs WHERE "colt_model_no" = '646'

Question: What is the rear sight type on the model with the acr muzzle brake device? 
SQL: SELECT "rear_sight_type" FROM m16_specs WHERE "muzzle_device" = 'ACR muzzle brake'

Question: Which muzzle devices are on the Colt 603? 
SQL: SELECT "muzzle_device" FROM m16_specs WHERE "colt_model_no" = '603'