How Orlando Shooter's Gun Differs From an AR-15 Shooting renews debate over semiautomatics By Newser Editors, Newser Staff Posted Jun 15, 2016 12:44 PM CDT 278 comments Comments File photo of an AR-15. The weapon used in Orlando was a Sig Sauer MCX rifle. (AP Photo/Charles Krupa) (Newser) – The Orlando shooting has raised anew the issue of the powerful weapons used by gunmen in mass shootings. While police initially said Omar Mateen used an "AR-15-type assault rifle," they have since clarified that he used a Sig Sauer MCX rifle. A look at some of the coverage: The Washington Post looks at those two weapons and finds that they're similar in broad terms: "a highly portable, customizable, easy to operate and accurate rifle." But one big difference is in the mechanics of how the bullet is propelled and the next round readied. It's "direct impingement" vs. "piston gun," as the Post explains here. The Sig Sauer can use magazines common to other semiautomatics, "but otherwise has no major parts that interface with AR-15s in any way, shape or form," says the Bearing Arms blog. (The post bashes media ignorance on the subject.) The Economist digs into the controversy over use of the term "assault rifle," which gun-rights advocates say is inaccurate because a gun such as the AR-15 "shoots only one round per trigger-pull." Orlando station WFTV offers a primer on topics such as the difference between semi-automatic and automatic weapons. (The AR-15 and the Sig Sauer are in the first camp; the military's M16 is in the latter.) PBS NewsHour did a segment on the AR-15 here. A Philadelphia Daily News columnist explains how she bought an AR-15 in seven minutes. Two Huffington Post writers got it done in 38 minutes. A New York Daily News writer fires an AR-15 for himself. He's "mostly terrified" as a result. Though he's taking flak for saying he got a temporary case of PTSD. FiveThirtyEight looks into the complicated topic of how such weapons are covered under gun laws.