Punching high into the blue Caribbean sky, test shots by the High Altitude Research Project of Montreal's McGill University are proving the value of a new space-research tool -- the large-calibre bombardment gun. Modified to fire instrument-carrying, streamlined projectiles which weigh but a fraction of the normal one-ton combat shell, the Canadian university team's research weapon is lobbing gleaming, finned bullets up to heights of 70 miles. After installing a 16-inch ex-naval gun on a sun-drenched beach on the coast of Barbados in the West Indies, the space researchers fired six test slugs early this year followed by a series of Martlet space-projectile shots. The aerodynamic Martlet, designed by McGill staff members, is opening a new window on high-altitude and outer-space research. For a fraction of the cost of ground-fired rocket packages, the Martlet provides a compact instrument container that can be fired to specific parts of the earth's outer reaches with rifle-shot accuracy. Canada's university team of scientists and engineers is exploring an exciting aspect of space technology -- using the energy that comes from the crash of big guns.