No personal experience, but have read a number of reports.
Two kinds of adapters it seems, short, chamber only, and longer (16-18: IIRC.
Chamber is so-so iffy accuracy, lt 50 yard accuracy at best. More like 30-35 yards.
The ones with the actual barrel use a rubber washer/plug to keep the rifled or smooth bbl centered, accuracy is bettern until you disassemble it and re assemble, then afjustments for centering start all over again,
Procedure is insert cartridge into adapter, insert adapter into chamber/barrel. Fire, remove adapter ( of chamber only) poke out spent case and repeat.
The adapters with an actual bbl run around $200.
Personally ... not for me.
But YMMV!
Regards,
...