In the game you will have lots of battles, but the DMG (damage) on your primary will make all the difference. The higher the DMG level, the easier it will be. The DPS (damage per second) does not mean everything. For those who want to continue using a rifle, the Marksman rifles will be your best bet. They have longer reload times and smaller clips (until you upgrade), but if you aim it correctly they will result in one shot kills. Using a shotgun as your primary is not recommended as most of your battles in the beginning will be medium range, but it would be perfect for close range combat.