[B_s1de]

I think it would simply re-engage the sector gear, let's say half-way on the piston. So, your next shot would appear more responsive or "efficient" where it is not really.

We say its more efficient in full auto because the motor does not need to break from a stopped position every shot.

Full auto would be pictured as this:
That's like starting a manual transmission car after a stop. You need more time and clutch play when you're on first gear. If you do it "the american way"(quebec expression or maybe elsewhere, which means to do a stop without completly stopping), you can get on second gear, thus starting faster.

Looks like that to me.