You will never be able to establish a consistent, accurate rate of deceleration equal to that established by the autobrake system. Further, when you take it upon yourself to forgo the recommended system (autobrakes), you still use the same system that operates the autobrakes: the antiskid system. (If you're foolish enough to turn that off, too...you get what you deserve).
When in autobrakes, one always has the option of applying manual braking, increasing the autobrake setting, or disconnecting the autobrakes altogether (which happens upon application of manual braking, anyway). Pilot override is always an option.