SWEP:SetScale not working

[turkeyfag]

function SWEP:DoImpactEffect( tr, dmgtype )

    if( tr.Hit && !tr.HitSky ) then
    
        local effect = EffectData()
            effect:SetOrigin( tr.HitPos )
            effect:SetNormal( tr.HitNormal )
	    effect:SetScale( .5 )
        util.Effect( "explosion", effect )
        
		end

    return true
end

Trying to have a small explosion appear near where the swep round lands, just an effect, no damage.