Greenhouse gases are the cause of Greenhouse effect.The greenhouse gases which include CO2, Methane etc. trap the heat in the Earth's atmosphere and don't allow it to escape.
The weapon is fitted with a Leupold Mark 4. The rifle is also similar in appearance to the TAC-338 rifle that Kyle used in real life. McMillan TAC-338A sniper rifle with Harris bipod, Leupold Mark 4 scope, and AN/PVS-22 Universal Night Sight - .338 Lapua Magnum. Kyle taking aim with the rifle. Right side of the rifle.
1 Chris Kyle was the most successful sniper in American military history. 2  He claimed 255 lives during four tours of Iraq before retiring in 2009. 3  His life is the subject of a new film tipped for success at the Oscars.  In 2013 Kyle was shot and killed by a friend at a shooting range in Texas.