Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the p max (bar) in the pistol where the chambering is .45 ACP?

### Inputs:
table_name: table, columns: ['Chambering', 'P1 diameter (mm)', 'A external (cm 2 )', 'P max ( bar )', 'F bolt ( kgf )', 'F bolt']

### Response:
SELECT MAX P max ( bar ) FROM table WHERE Chambering = .45 ACP