I bought up a bunch of Harry Owen's brass and blued steel cartridge adapters many years ago (before he died). Mostly they were bought for resale, but I also played around with them myself off and on over the years and still have a few I kept for personal use. How good a job they did seemed to depended on what was being adapted to what and in what firearm, but some of them were really quite good. I remember the 22LR/MAG in 222 Rem and the 22 Hornet in 223 and 22-250 as being quite accurate for me. Maybe 10 years ago or so I bought a bunch more made just for 22LR/MAG and 22 Hornet use in TC pistols/carbines. Much easier/faster to use than the plunger style adapters. I also have adapters for shooting lead pellets in several 17 and 22 caliber cartridges using only a primer. Some of these work well, some not so well, but they are a great practice tool when you can't get out of your garage/yard and to a safe shooting place. A gent in Alaska bought out Bill and still makes and markets at least some of the Owen adapters as far as I know.
Have also played around with a couple of barrel insert adapters (1 pistol, 1 shotgun). Naturally they work much better than chamber adapters, but at a very much higher cost.
