According to the Wall Street Journal, Activision had previously reached a secret agreement with weapons manufacturer Remington to use the company's Adaptive Combat Rifle in 2009's "Call of Duty 6: Modern Warfare 2."

The deal was detailed in internal Remington documents that legal counsel obtained during a lawsuit filed by parents of children killed in the 2012 Sandy Hook Elementary School shooting, the report said.

In the 2012 shooting, 26 people were killed, most of them first-grade elementary school students. The murder weapon in the attack was a Remington AR-15. The company settled the lawsuit last year for $73 million.

There is no financial transaction involved in placing ads in Call of Duty, but both Activision and Remington have agreed to keep the agreement confidential.

Internal documents from Remington and its Freedom Group company show that weapons manufacturers try to strike such deals to increase their appeal to younger audiences.

"As urbanization increases and shooting/hunting areas decrease, the primary way potential young shooters are exposed to firearms and ammunition is through virtual gaming scenarios," a memo from the Liberty Group reads.

Executives also talked about building brand preference among the "next generation" and winning "our fair share of these younger consumers."

Another memo from the company states that while the group does not allow its brand to be used in games where players can target "non-military bad guys," it has no problem using replicas of the weapons it manufactures in such games. "History has taught us that people look for forced brands," the memo said. "The lack of direct branding helps insulate us from direct identification while still benefiting from playing the game."

John C. Thrull, Remington's former vice president of firearms product management, told the Wall Street Journal that company executives were unaware of the multiplayer mode in Call of Duty when the deal was struck. "We were unfamiliar with the concept of online lobbies for players to participate in Team Deathmatch," Thrull said. "I believe if someone had known at the time the way these games evolved as we know them now, the decision would have been different."

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