Did he have to pull a trigger to discharge each round?

Yes.

But the fact is that the volume of fire produced by Lanza’s semi-automatic arsenal was substantively the same as the fully automatic “gangster guns” effectively outlawed by Congress in 1934 and again in 1968.

That ban did no real violence to the 2nd Amendment, so it’s hard to see how constraining the availability of high-tech military knockoffs would do so today.