It mainly depends in the range you hit your target from.
Short range: 18~24
Middle range: 16~22
Long range: 14~20
Its great, probably best of all LMGs because of its does not cover a larger portion of your screen like the PKM or M249, thus allowing you to see whats happening around you due to the smaller iron sights.
It's extremly effective from short to mid ranges due to the MG3's incredibly fast firing rate allowing it to clear rooms or win CQC easily or kill at a range, it is somewhat accurate but loses it accuracy when firing at a target from afar.
This weapon has 80 rounds Belt with another 80 rounds in reserve. This gun has a reload time of 7.1 seconds.
The MG3 is best when burst fired as the high recoil leads to low accuracy. A trick with the MG3 is to drag your mouse downwards as you fire, keeping the gun from firing over the heads of targets. Because of this the MG3 is best on maps like Sharqi where there are close-quarters engagements. A quick hip spray will take down most targets.