I scanned every store and online vendor I know of . There is only ONE box available and its on Gunbroker . The auction ends July 5 at 8;21pm
As of this post the highest bid is $26 bucks . There is $8 shipping fee . It says its 25 rounds but its not. Its one box of 20 . But I think you should be able to site the gun in with less than 10 . Its the only low recoil box available in the 20-25 places I searched . Hornady Custom Lite Low Recoil 120grain SST . It should do the job.

https://www.gunbroker.com/item/904283909