Magnum rounds made it so that you'd do 25% more damage per shot. It favored the M95 because of its extended damage drop off range. For one hit body shots upto about 38 meters. Other sniper rifles needed to be even closer.
This means there's really not a proper choice here. Either you plan to stay at range and the range finder is a must pick, or you plan to aggressively snipe and magnum rounds are a must pick. Magnum rounds had a counter called Ceramic Body Armor. I never liked it because it made close range sniping really inconsistent.
What we have instead is the sweet spot mechanic, which effectively does the same at a certain distance. For example, alllwing you to one shot players in the chest in between 80-100 meters.