Elm St (S) side activity BEFORE Frame #313: (1) Mr Willis stepping back onto the curb, (2) Willis's daughter running down Elm St curb area, (3) Bob Croft raising/lowering camera, (4) Old Lady frantically waving handkerchief at JFK, etc, etc, etc. The (N) side of Elm St looks like a crowd scene in the Hollywood Wax Museum.
Oswald's shot-1 ricocheted offa the overhead signal arm at say pseudo-Z105.
I suspect that the noise would be moreso out front of the Carcano, ie moreso on the S side of Elm.
I suspect that the noise would be heard moreso by gawkers on the S side, facing the Carcano.
Rather than the gawkers on the N side, with Carcano above & behind.
Likewise Oswald's shot-2 at Z218.