[HELP] How to make custom weapon have silenced sounds?

[YuriBengala]

Hey folks, so im working on a weapon mod, and basically i can't make them have sound while supressed, i already tried to add commands to Item_Modifiers but it doesn't work

 

<sovietpack>
<append xpath="item_modifiers">
	<item_modifiers>
		<item_modifier name="modGunSoundSuppressorSilencer" installable_tags="gun" blocked_tags="revolver,flaredBarrel" modifier_tags="barrelAttachment" type="attachment">
			<item_property_overrides name="gunMP-133">
				<property name="Sound_start" value="pump_shotgun_s_fire"/>
				<property name="BarrelOffset" value="0,-0.0322,0.4516"/>
				<property name="BarrelScale" value="1.1,1.1,1.5"/>
		</item_property_overrides>
	</item_modifiers>
</append>
</sovietpack>

any ideas how to fix this?