Just saw an odd devise at a gun show today, an auxiliary chamber in 30-06 caliber, that held a .22 RF cartridge. I asked the owner of it, how can that shoot accurately out of a .30 caliber barrel ? He showed me the instructions, and the small .30 cal lead "caps" that fit over the nose of the .22 bullets. Kind of like putting a .30 cal hollow base wadcutter bullet over the .22, and inserting the devise in a 30-06 and firing. It was built like the old Marbles chambers, and was built by a company called Alex Inc. Bozeman, MT.
Has anyone ever seen one, or know if they ever worked. I thought it was a clever idea, if it would shoot with some accuracy out to 25 yds or so. I wish I could have gotten a good photo of it, and the instruction sheet, to explain it to you better.