Factory blanks are sometimes readily available but difficult to find. I don’t see blank ammo stated in almost any on the nationwide catalogs that list Reside ammo. Now then Aged Western Scrounger has a few although not in just about every caliber. Navy Arms sells five in one blanks but https://strapweaponshop.com/product/triple-r-munitions-223-5-56-nato-blanks-100-rounds/