BudsGunShop.com - Can this chamber and shoot 9x21

Michael, this head spaces on the case mouth Sir. Cheers and stay safe!

Ruger response from when I asked them your question.
"From what I understand the case on the 9x21 cartridge is longer than the standard 9mm cartridge. I would not use it in the SP101 revolver. For more info, please contact our customer service dept. to speak with a tech. 336-949-5200; M-F; 8-5 ET."

I'm thinking it probably wouldn't be a good idea. I couldn't find anything definite either way but I messaged Rugers customer service and haven't heard back, they are probably closed by now, but I'll update when I get an answer.
Or if you'd like to contact them
ruger.com/footer/contact.html