Daniel E. Watters, firearms historian, has supplied an image (source unknown) of the four finalists (ARES and McDonnell Douglas' entries were not finished by the field testing stage) for a new general service rifle, during the last cycle of searching for a replacement for the M-16 (introduced in the early 60s):
The four candidates, from Steyr-Mannlicher, AAI, Colt, and Heckler & Koch, were unveiled on 13 APR 1989.
Read a description of each [by Daniel] in the continuation.
An earlier A-C-E post contains an article noting the Army elected, 13 months ago this month, to stay with the M-16A2, stating none of the candidates provided a 100% improvement, which was deemed necessary to justify the cost of a switch. The study took 7 years and cost the taxpayers $32 million. The final 7-volume report was 2.5 ft. high when stacked.