The .22lr conversion kit is a good option.
For a seperate handgun, I'm partial to Rugers. However, easy to disassemble the Mark III is not. Maybe a used Mark II?
I don't know how easy the Browning BuckMark is to disassemble or the S&W Model 21.
I do know my Ruger Mark II .22/.45 [plastic framed, but the straight Mark II has the same reliability/accuracy] doesn't care which brand of ammo I send down the pipe: It likes them all.
Ciener does make a conversion kit for the Beretta 92/96 also. Ciener is not the most user friendly companies out there. I have a conversion kit for my Hi Power and it works fine. others have had problems. Ciener is almost impossible to get hold of, except through registered mail. Not my favorite company, but no one else is making a reliable/accurate BHP conversion kit, so I was stuck.
They DO offer them for Berretta. His design was the basis for the Kimber 1911 conversion kit also, just FYI. They have since changed their design, but I can't see a significant difference from pictures.