The soldiers in this movie are being trained for combat in Vietnam. The current issue weapon of that time period was the M-16A1 rifle. This is different from the weapon seen on the movie poster as that is an older US Air Force M-16. This can be noted as the Air Force model has a three prong flash hider but the M-16A1 has a bird cage style flash hider which was the weapon used throughout the movie.
While at the pistol range, Wilson challenges Bozz with a M1911 .45 pistol. After the encounter, a SSG comments the pistol is 'jammed'. It is not jammed, as the slide is in battery so there is no stoppage of the weapon. It may be a misfire, but not a jam.
All soldiers reporting for AIT in 1971 would been wearing the National Defense Service Medal (ribbon) on their khaki or service dress green uniforms. None of the actors have the NDSM on their uniforms.
In the final scene when Paxton comes out to meet the bus, he is wearing the Service Dress Green uniform. The uniform is missing the lapel insignia (brass disk with US) on both sides and the National Defense Service Medal. In addition, if he had successfully completed Infantry AIT, he would have blue disks behind the lapel insignia and there would be crossed rifles on the left disk. There would also be a woven blue cord over the right shoulder.