Shot and powder bushings from PW, Bair/Pacific/Hornady, RCBS and Spolar are interchangeable, so you have some options based on what you can find that will fit. None are easy to find in stock, as shotshell reloading has become much less common in the realm of high component cost, shortages and cheaper promo load shells. As mentioned the adapters to use Mec bushings are also an option, as Mec bushings are somewhat more commonly found.