<aura:component implements="force:lightningQuickAction" access="global" >
      <aura:handler name="init" value="{!this}" action="{!c.createRecord}"/>
</aura:component>

({
   createRecord: function(component, event, helper) {
      var createRecordEvent = $A.get("e.force:createRecord");
      createRecordEvent.setParams({
         "entityApiName": "MUSW__custom_obj__c",
          "defaultFieldValues": {
        'Name' : 'System Number'
        }
      });
      createRecordEvent.fire();
   }
})