Al butterknife handles I've used, required me to deliberately grasp the handle between my finders to operate, rather than merely hitting it with my palm to lift and extract, then slaming it forward with the palm to feed and close on a fresh round. The deliberate movements were slower - cannot see any situation where that could be faster than a round knob.

In proper speed operation of a SMLE bolt gun, the forefinger and thumb constantly grip the bolt's knob for operation, while the Saturday Night finger of that hand pulls the trigger. A practised solider could match a semi's rate of fire.