user: Question: What is the max pressure for the 468ft•lbf (634 J) muzzle energy?
Columns: ['Cartridge', 'Bullet weight', 'Muzzle velocity', 'Muzzle energy', 'Max pressure']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['.38 Short Colt', 'gr (g)', 'ft/s (m/s)', '181ft•lbf (245 J)', '7,500 CUP']
SQL:

assistant: SELECT "Max pressure" FROM "Table" WHERE "Muzzle energy" = '468ft•lbf (634 J)';