The colt M16A2 is a variant of the M16 assault rifle. Unlike the original M16 and the M16A1, was incapable on fully automatic fire, firing in 3-round bursts instead.
The M16A2 was the standard issue weapon for the InGen Security Division in 1993. Robert Muldoon, the park's game warden probably chose the weapon to arm the park's ranger's and personnel with due to it having good firepower which would prove useful in the event that a dangerous dinosaur escaped its enclosure and lethal force was needed. Although Muldoon himself preferred the Franchi SPAS-12 as his personal weapon of choice, he armed most of the park's rangers and workers with the M16A2s especially during dangerous operations such as transferring the raptors to their holding pen. Muldoon himself kept an armory which was well stocked with M16A2s as well as SPAS-12s and also kept such weapons at key points in and around Jurassic Park's compounds such as the emergency bunkers and the visitor's center for use in the event of an emergency. During dangerous park operations such as dinosaur transfer, Muldoon often had his men armed with M16A2s to act as backup to the men armed with tasers so they can be ordered to shoot the dinosaurs should they pose direct threat to personnel and or visitors such as when he oversaw the raptor transfer.
The M16A2 was in the service of the Costa Rican National Gaurd in 2015.
Behind the scenesEdit
Some of the M16A2 used in the movie weren't actual M16A2s, but M16s with A2-style handguards meant to impersonate the latter. This concept has been used repeatedly in many movies.