are we talking about a shell (or a spent case?).
IF you are talking about hand jacking a live round out of the weapon then that can be several problems, many of which is the shooter!
first there is no way a human can operate a slide rearward as fast as the gun does when its fired, additionally if you are trying to eject a full unfired round its considerbally heavier/ longer than a fired case.
the only reason really that this would even come into play is if you needed to do a clearance operation on a malfunctioning round.
while this is important again if talking about a unfired round then you got to give the slide a fast , firm yank rearward and kind of toss the weapon to the right and up to throw the full unfired round out of the gun.
now if its a fired round (spent case) then thats another discussion.
again now i don't know you expertise with weapons or exactly what you are talking about, only trying to answer.