Not all bar action hammer guns had the pin (screw post) in the mainspring area.
Picture of Quality AA L.C. Smith, one of two known to exist.

Instead of a pin, the area for the mainspring was milled out to half the height of the mainspring.

I refer to this type of lock, a 5 pin 2 screw bar action lock. This 5 pin was used from 1884-1889 when it was then changed to a 6 pin 2 screw bar action lock.
Only one true pin and that is the sear axle.

David