  In previous papers it was shown that gamma rays with characteristics similar
to those of the gamma-ray bursts (GRBs) observed by astronomers may arise from
suitably shaped nonuniformities in the Big Bang in a quasi-spherical Szekeres
(QSS) model. The gamma radiation arises by blueshifting the light emitted by
hydrogen atoms at the end of the last scattering epoch along preferred
directions that exist in QSS models. However, the durations of the gamma
flashes and of their afterglows implied by the model were much longer than
those of the observed GRBs. In this paper it is shown that for the gamma-ray
flash a duration of correct order results if the blueshifted radiation, on its
way to the present observer, passes through another QSS region where it is
deflected. The angle of deflection changes with time because of the
cosmological drift mechanism, so the high-frequency ray will miss the observer
after a while. It is shown by explicit numerical calculation that a gamma-ray
flash will no longer be visible to the present observer after 10 minutes.
