The G36C has been introduced in the 1.7.5 DayZ patch.
The Heckler & Koch G36C is a modified G36A assault rifle, the "C" standing for compact. It has a shorter barrel than the G36K, and a four-prong open-type flash hider. The barrel, handguard and gas piston is considerably shorter than its parent rifle. The reduced barrel length leads to slightly reduced accuracy at longer ranger, as well as making the bullet drop slightly quicker than if fired from a standard length barrel.
Presently the weapon will only accept Mod:G36 Mags and Mod:G36 SD Mags as ammunition.