Killing Season is a 2013 American-Belgian action drama thriller starring Robert De Niro and John Travolta as two veterans of the Bosnian war, one an American Colonel and one a Serbian soldier, who face off against each other again in the Appalachian mountains. The film was directed by Mark Steven Johnson (2003's Daredevil).
The following weapons were used in the film Killing Season:
Colt AR-15 Sporter CarbineWhile in Bosnia, Col. Benjamin Ford (Robert De Niro) appears to carry a weapon that resembles a Colt AR-15 Sporter Carbine. This is likely a replica.
Some US soldiers appears to be armed with M16A2 rifles. These also are likely replicas.
(Faux) M16A2 (Bulgarian AR)
At least some of the M16A2 rifles used in the film appear to be mocked up Arsenal AR's. Because this production was partially filmed in Bulgaria, these are likely the same mockups seen in other productions also filmed in the area including Universal Soldier: Regeneration and The Shepherd: Border Patrol.
Local militia fighters in Bosnia are armed with AK-47 assault rifles.