Counter Strike Online Wiki

For previous stage, see Mechasaurus MK-3.

Mechasaurus MK-4 is a Unique grade assault rifle in Counter-Strike Online.


This item can be obtained from 2021 Season 11.
Empty slot This weapon has Part System installed.

The completed assault rifle that fires 60 rounds of 5.56mm bullets, created during the restudy of the Aegis Institute's Transform System after development was halted. The Transform System has been applied, which allows the use of burst shots without consuming bullets and causes rounds to explode, burning nearby enemies after transforming into Berserk mode upon landing a certain number of shots.



Release date[]

  • South Korea: 16 December 2021.
  • China: 22 December 2021.
  • CSN:S & TW/HK: 29 December 2021.

Comparison to MK-3[]

Mechasaurus mk3

  • Higher zombie damage with Parts
  • Runaway mode has explosive bullets
  • Same price ($400]
  • Same human damage (17)
  • Same accuracy (90%)
  • Same recoil (10%)
  • Same rate of fire (88%)
  • Same speed reduction (9%)
  • Same knockback power (12%)
  • Same stun power (61%)
  • Same reload time (2.5 seconds)
  • Same magazine size (60)
  • Harder to obtain
  • Higher level in Zombie Z



  • Upon release, it was required to hit enemies to count for the activation of the runaway mode, similar to the JANUS system. However, a patch of the following week changed it so that the act of firing alone will count towards the activation.