With the right rolls, you could have a sniper that can fire 11 rounds before needing to reload. To get it, you'll have to run the Insight Terminus Nightfall. Here's a guide for farming it, getting a high score and for unlocking the Triumph Capture Completionist!
More Destiny 2 Nightfall Speedrun Guides: https://www.youtube.com/playlist?list=PLwKum4Ud-roH8tMPeQzjVnSna_4h6TsTF
More guides for Joker's Wild! https://www.youtube.com/playlist?list=PLwKum4Ud-roFOZLw_gaJHVpyZ_CXUW6sW
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"OB1 by RalphReal" https://www.youtube.com/watch?v=WsrLp5K_Zd4