Kill Ping writes: “A couple of weeks back, Valve announced its newest weapon for Counter-Strike: Global Offensive called the MP5-SD. However, since the MP5-SD is new to the game, the silenced SMG was released only for the games casual modes including Deathmatch, Casual matchmaking and even Workshop maps. With the developers releasing a brand new CS:GO update today, the MP5-SD is now available to use in the official competitive matchmaking mode”.
Source: N4G PC CSGO Update 1.36.5.4 Brings MP5-SD In Competitive Matchmaking