Table: ar15_variants_3
Columns: colt_model_no
diemaco_model
stock
fire_control
rear_sight
forward_assist
barrel_length
barrel_profile
barrel_twist
hand_guards
bayonet_lug
muzzle_device

Question: What is the value of barrel twist when the barrel profile is SFW?
SQL: SELECT "barrel_twist" FROM ar15_variants_3 WHERE "barrel_profile" = 'SFW'

Question: What kind of hand guards are associated with a rear sight of A1 and stock of A2?
SQL: SELECT "hand_guards" FROM ar15_variants_3 WHERE "rear_sight" = 'A1' AND "stock" = 'A2'

Question: How many inches is the barrel length when the rear sight is weaver and the barrel profile is A2?
SQL: SELECT "barrel_length" FROM ar15_variants_3 WHERE "rear_sight" = 'Weaver' AND "barrel_profile" = 'A2'