Recreation of the quick action modal with header and footer to give you control over the quick action buttons. Enjoy!

Salesforce Lightning Component Quick Action Modal

<aura:component implements="flexipage:availableForRecordHome,force:hasRecordId,force:lightningQuickActionWithoutHeader"
                access="global">

  <!-- modal size fix -->
  <style type="text/css">
    .cFulfillmentReceivePurchaseOrder.slds-modal__container {width:100%;padding:0;margin:0;}
    .cFulfillmentReceivePurchaseOrder .slds-modal__content {padding:1rem;}
    .slds-modal__content {padding:0;height:auto !important;max-height:100% !important;}
    .forceChatterBasePublisher :not(.PHONE) .cuf-content {padding:0;}
  </style>
  <!-- end modal size fix -->

  <!-- component container -->
  <div class="slds-modal__container">
      <header class="slds-modal__header">
        <h2 id="modal-heading-01" class="slds-text-heading_medium slds-hyphenate">Modal Header</h2>
      </header>
      <div class="slds-modal__content slds-p-around_medium" id="modal-content-id-1">
        <p>Sit nulla est ex deserunt exercitation anim occaecat. Nostrud ullamco deserunt aute id consequat veniam incididunt duis in sint irure nisi. Mollit officia cillum Lorem ullamco minim nostrud elit officia tempor esse quis. Cillum sunt ad dolore
          quis aute consequat ipsum magna exercitation reprehenderit magna. Tempor cupidatat consequat elit dolor adipisicing.</p>
        <p>Dolor eiusmod sunt ex incididunt cillum quis nostrud velit duis sit officia. Lorem aliqua enim laboris do dolor eiusmod officia. Mollit incididunt nisi consectetur esse laborum eiusmod pariatur proident. Eiusmod et adipisicing culpa deserunt nostrud
          ad veniam nulla aute est. Labore esse esse cupidatat amet velit id elit consequat minim ullamco mollit enim excepteur ea.</p>
      </div>
      <footer class="slds-modal__footer">
        <button class="slds-button slds-button_neutral">Cancel</button>
        <button class="slds-button slds-button_brand">Save</button>
      </footer>
    </div>
  <!-- end component container -->

</aura:component>