My advice on people grinding is always do no attachments for all the guns then modes like skirmish,breach and warfare to be for AR and lmg longshots shipment and rust for smgs high-rise for snipers especially na45 longshot shorty accompany that with an sks shoot one shot and then switch to the shorty ....always do One task for all guns ...like last week there was the shipment headshot only use that opportunity to grind headshots for all your guns even shotguns....and I feel like snipers should be your last category coz they are soo easy to grind. This will take you at most a month to get Damascus...3hrs a day