Personally I prefer grabbing a DMR that gun is amazing, 3 good shots to the face and they're flipping over as if their head has been pinned to that brick wall 20 meters behind them.
Well yeah obviously I prefer the dmr, I'm just saying the magnum is a pretty beast weapon to start out with if you're playing normal slayer, especially with the 2x Zoom.
And the dmr takes 5 headshots to kill so idk where you came up with 3 good shots to the face