I don’t think you have to worry too much about the 620/619/520’s. That was S&W’s first shot at the two piece barrel. Allegedly, some 620’s barrel liners were over torqued resulting in the breakage at the muzzle end flange. In the past 15 years I’ve seen exactly one example of this on this website, so I did happen, but not nearly enough for me to care. I don’t recall hearing about this issue with the 619, 520, or the 64’s that were built with the same two piece set up. I own two 620’s. They are remarkably accurate. I use one as tool for testing consistency of my hand loads and the other is a spare since these were practically given away on gunbroker for less than $500 years back. Weak pricing was consistent for used IL guns back then. I have at least 4000 rounds down the pipe on mine. No issues to report. Very smooth trigger, and very accurate.