user: Question: What is Length, when Barrel Length is 750mm / 29.5 in?
Columns: ['Nation', 'Model', 'Length', 'Barrel length', 'Weight']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Denmark', 'Rifle 1889', '1328mm / 52.28 in', '832mm / 32.78 in', '4.275kg / 9.5lb']
SQL:

assistant: SELECT "Length" FROM "Table" WHERE "Barrel length" = '750mm / 29.5 in';