All the chamber adapters I've had were full length parent case design. I've had 223 adapters for 22LR, 22MAG and 22 Hornet, and in many other combinations for other parent cases from 22Hornet to 22-250 (about two dozen of them at one time in brass and steel from the original company that made them). No they do not hurt the chamber. They also do not shoot worth a damn for the most part.
Only ones I ever had that was worth their trouble was a TC type 222/22Hornet adapter that could shoot quite accurate to reasonable ranges; and a primer driven 22Hornet/22 Pellet adapter that filled the bill as a quiet/instant kill combo for pest control around the house. The 22-250/22Pellet adapter couldn't drive the Kodiak's fast/flat enough even with mag primers to insure instant kill pest control. The plunger type adapters were way to much work to use IMO, whether in a TC or any other firearm. To me they turned out to just be a novelty. And IMO are not worth the price the last company to take over the business many years ago charges for them now days (MCA).
Far better but way more expensive would be the barrel inserts. But for around their asking price you could just buy a used barrel for your TC instead and be way ahead.
