50 years ago at the gun shows there were a lot of 30-06 to 308 conversion adapters available, they worked fairly well and came with a stuck shell remover so you could convert back to the original. I shot a few rounds out of them using South African surplus 308 and it worked well if not extremely accurate. Always wondered if that was due to the distance to the rifling or just the ammo. At my age I am much more impressed by reduced loads than chamber adapters. Using Unique and a reduced load of 10 to 12 grains, you can get 500 to 600 rounds at about the same performance of a 30-30 out of a 30-06, with the lower velocity cast lead bullets work fine, the lower pressures extend the case life, and using the old Lee loader which only neck sizes them and shooting them out of a single bolt action, they work fine. I don't know, but if you annealed the case mouth, they might last an even longer time. That means that for me the limiting factor is the primers as I have a few pounds of Unique for pistol use, etc, molds, a couple hundred pounds of wheel weights, and a couple hundred rounds of loaded 30-06. I shoot the reduced loads as my eyes no longer allow long distance shooting, my shoulder appreciates the reduced recoil, the lower sound signature keeps the neighbors a little more off my back, and the price is right. While it isn't a chamber adapter, different loads and different bullet weights and the ability to reload extends your possibility's to resupply your existing rifles and pistols. At .309 and reduced velocity, a about 150 grain bullet would work well enough for survival hunting and close in defense in every thing from a 30-30 to an AK47. Have any other members of the forum had any experience in doing this type of reloading? Most of the reloading seems to be done to improve accuracy and number of loads per pound of powder, etc, doesn't seem to be a consideration.