ObjectTemplate.HasStartEffect

MDT description

By default, this property is (1) true for a Projectile; it is set to 0 (false) when the projectile has no starting muzzle-flash effect. The starting effect used is defined by the parent FireArms object.

For example, for the defgun's muzzle flash, the following is done in the Vehicles/Land/Defgun/Weapons.con file:

rem *** DefgunGunBarrel ***
ObjectTemplate.create FireArms DefgunGunBarrel
... 
rem -------------------------------------
ObjectTemplate.addTemplate e_MuzzDefGun
ObjectTemplate.setPosition 0/0/9.2
rem ObjectTemplate.setPosition 0/0/0.5
ObjectTemplate.setRotation -179.999/0/0

This adds the muzzle flash effect. When the projectile is fired, it triggers the effect in the parent FireArms object in the desired location relative to the barrel of the gun.

Source and more details