user: Question: How many inches is the barrel length when the rear sight is Weaver and the barrel profile is A2?
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']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['715', 'C7', 'A2', 'S-1-F', 'A1', 'Yes', '20 in.', 'A2', '1:7', 'Ribbed', 'Yes', 'A2']
SQL:

assistant: SELECT "Barrel length" FROM "Table" WHERE "Rear sight" = 'Weaver' AND "Barrel profile" = 'A2';