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muzzleImpulseFactor AFM desynchronization
Acknowledged, NormalPublic


muzzleImpulseFactor on CfgMagazines, which are used by high-ROF CfgWeapons on helicopters, cause the helicopter to desynchronize for every other client and server after using that weapon. Recoil of the weapons in AFM is not handled properly.

This can most easily be observed by applying any muzzleImpulseFactor greater than {0, 0} to miniguns of the vanilla Little Bird in Multi-Player. Let the Pilot fly and shoot the miniguns (with AFM enabled!), after a few shots he will start flipping for every other non-local client. It is best observed when landing as the helicopter will try to interpolate between pilot's position/rotation and server's (or other client's). Upon getting out, the helicopter will flip and might explode.

This can also be observed on vanilla Kajman O_Heli_Attack_02_dynamicLoadout_F with it's auto-cannon, but in a very reduced rate (few hundred shots) as the auto-cannon has low-ROF. For this to work Pilot must be alone in the helicopter and use "Manual Fire".


Operating System
Windows 10 x64
Advanced Flight Model
Steps To Reproduce
  • Apply muzzleImpulseFactor = {1, 1}; to CfgMagazines (eg. 5000Rnd_762x51_Belt used by M134_minigun on an "AH-9 Pawnee").
  • Connect with 2 machines to a dedicated server.
  • First client with AFM enabled should fly around and shoot miniguns as much as possible.
  • Second client can observe desynchronization - more firing will cause more desynchronization.
Additional Information
  • Any muzzleImpulseFactor that is NOT {0, 0} will cause this.
  • Desynchronization can be immediately visible on high-ROF weapons.
  • Desynchronization is not visible with rocket pods or missiles (limited testing).
  • Desynchronization does NOT happen with SFM, only AFM.

Event Timeline

Jonpas created this task.Oct 13 2020, 3:53 PM
veteran29 added a subscriber: veteran29.EditedOct 13 2020, 3:54 PM

Seen by other clients like this:

Jonpas edited Additional Information. (Show Details)Oct 13 2020, 4:01 PM
JoramD added a subscriber: JoramD.Oct 13 2020, 7:06 PM
dedmen changed the task status from New to Acknowledged.Oct 13 2020, 7:54 PM
dedmen set Ref Ticket to AIII-53417.