user: Question: With what type of chambering is the F bolt N (lbf) and the P max (bar) 3900?
Columns: ['Chambering', 'P1 diameter (mm)', 'A external (cm 2 )', 'P max ( bar )', 'F bolt ( kgf )', 'F bolt']
Types: ['text', 'text', 'text', 'real', 'real', 'text']
Sample row: ['.22 Long Rifle', '5.74', '0.2587', 1650.0, 435.0, 'N (lbf)']
SQL:

assistant: SELECT "Chambering" FROM "Table" WHERE "F bolt" = 'N (lbf)' AND "P max ( bar )" = 3900.0;