Originally Posted by 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.
Not quite. As explained above, the P90 has a 2 stage trigger. When in semi, you can only depress it about halfway, which makes it fire semi. With the selector in full auto, it really only unlocks the trigger allowing you to pull it all the way. So stage one still gives you semi, but going all the way goes to auto. So squeezing off signle shots with the selector to auto is exactly the same as being in semi.