use this code

this a perfectly working laser rifle
;------------------------------------------------------------------------------
Weapon Lazr_RangerLaserRifle
PrimaryDamage = 5.0
PrimaryDamageRadius = 5.0
ScatterRadiusVsInfantry = 0.0 ;When this weapon is used against infantry, it can randomly miss by as much as this distance.
AttackRange = 100.0
MinimumAttackRange = 4.0
DamageType = SMALL_ARMS
DeathType = BURNED ;;NORMAL
WeaponSpeed = 999999.0 ; dist/sec (huge value == effectively instant)
ProjectileObject = NONE ; dist/sec
LaserName = 'your new laser effects goes here'
LaserBoneName = MUZZLE01
FireFX = 'your new fire effects goes here'
RadiusDamageAffects = ALLIES ENEMIES NEUTRALS
DelayBetweenShots = 400 ; time between shots, msec
ClipSize = 4 ; how many shots in a Clip (0 == infinite)
ClipReloadTime = 700 ; how long to reload a Clip, msec
ProjectileCollidesWith = STRUCTURES WALLS
End
PS: dont edit infantry models if u dont know how to properly rig them

or face an evil bug
