In the late 1970's I became enamored with the whole thought of a 30 Carbine necked down to 22 and firing a fast bullet. I wanted a gun like that from the first moment. And in late 1982/early 1983, I found on Iver-Johnson M1 Carbine chambered in 5.7mm Johnson in a gun store in Batesville, Arkansas. The stamp on the receiver indicates it was made in Plainfield, New Jersey. It came with a set of RCBS reloading dies and a small quantity of loaded ammunition. The dies have a date code of "79" stamped on them which I take it to suggest that they - and probably the associated rifle - were made in 1979.
It took two rounds of the ammunition that had come with the gun to realize it had been loaded way too hot and the other rounds were disassembled, the powder discarded and the other components salvaged. It also became apparent to me that the cases had been formed by running 30 Carbine cases into the sizer die without the use of any forming dies. It didn't seem to me as if that was good practice and so I shelved the gun until I could get some information about it. I later discovered that several reloaders formed their brass in the sizer and reported no problems.
In 1986, I was in Pine Bluff, Arkansas, and the owner of a gun store there had a copy of an old Pacific reloading manual that had charges for the 5.7mm Johnson in it. At this time, I also had the chamber cast and was told the bore was 0.224. I would later have reason to question the accuracy of this cast. The Pacific data also proved too hot for the gun. I was getting the usual pressure signs of primers backed out of their pocket, flow into the firing pin channel and distortions of the markings on the case head.
I once again shelved the gun.
By 1993, I had landed in Texas (I think of it as temporary exile) and had purchased forming and trim dies from RCBS to go along with my existing set of reloading dies. I also had gotten the load data from Cartridges of the World. I also received some additional reloading information and technical data from RCBS and The American Rifleman. At that point, I tried reloading but stepped the starting load back to 11 grains of IMR-4227 with a 40 grain bullet to be sure I was below the pressure danger zone. 11 grains would not cycle action, but 11.5 grains would. Still performance was anemic and accuracy poor at this load. I also tried Hercules 2400 and IMR-4198 powders as well and had no better results with them; as a general rule, any powder that would cycle the action produced signs of excessive pressure.
Since then, I would revisit the cartridge occasionally and try to work out what was going wrong. With the arrival of the internet, I was able to communicate with other reloaders, but until recently was unsuccessful finding anyone who had any first-hand knowledge of the rifles or the cartridges. Through the Iver-Johnson pages on http://m1carbinesinc.com/, I eventually got connected to Edward Rice Johnson, Col. Johnson's son, who was able to provide a considerable amount of information about the rifles and 5.7mm cartridge and led me here.
One of the things Mr. Johnson pointed out was that some of the commercial manufacturers used barrels that were either 0.223 or somewhere between 0.223 and 0.224 (call it 0.2235) and that for these barrels, a 0.224 bullet might simply be too big. A subsequent cast of the chamber and bore revealed 1) cases formed using the RCBS form, trim and sizer dies matched the chamber very closely, and 2) that the bore of the barrel was "indeterminate", which upon closer questioning of the gunsmith means it was neither 0.223 or 0.224. I take it this means it is one of the barrels I have chosen to call 0.2235.
Rather than asking my cartridges to swage my bullets on their trip down the barrel, I have obtained a quantity of Sierra 0.223 bullets and will embark upon loading those starting later this year.
Sorry for the long introduction, but I wanted you to know where my 30+ year long adventure to load this cartridge has taken me, If there is anyone out there with experience reloading this cartridge, I would appreciate any help you are willing to offer.