M1 30 cal rechambered to 22 cal

We have one in that cal, 5.7MMJ Spitfire, is really a fun cartridge. Best if you get it or have it would be to slug the chamber to be sure of what cartridge it takes as their were a couple other '22's made. If you are not into reloading their is no commercial ammo made, is quite easy to make your own. If we can be of any help just ask. Cheers

Dear SWANEEDMB

Scandia, I think it best for you to take the carbine to a gunsmith and have it checked for the headspace and they can do a chamber slugging, who knows who may have made this carbine. Best be safe than sorry, just my 2 cents.

Only thing I could find on it was written in Spanish....I think.

Most of us have our little quirks and I surely have mine, but for the life of me I just don't understand why somebody would want a firearm that nobody makes ammo for. For me, if it's not a caliber I can find on about any street corner, I don't want it. That limits me to 22LR, 45acp, 9mm, 38/357, 5.56, 7.62x39 and 30-carbine is my "have to hunt it or reload for it" round.

A number of years ago there was a company , IWI not sure what that stood for at this late date, but they were affiliated with IMI, Israeli Military Industries and they sold M1 carbines chambered in .30 carbine or 5.7MMJ. They were located in Texas. The ammunition, 5.7MMJ, was made by a Texas gun range specifically for IWI. When IWI sort of went out of business the ammunition was available for a while from Gun Parts Corporation in New York.
  I had purchased 100 rounds with my carbine and several years later wanted more and it was unavailable.
  Reloading this caliber at the time was going to prove pretty expensive as I would have had to purchase the reloading dies as well as the re-sizing dies and that would have come to about $300 plus cases, bullets, powder, etc. Fortunately, one of the boxes that the original ammunition came in had the name of the gun range/manufacturer. I called them to see if they had any more ammunition but they said no because there was not a very big market for it. I explained my problem with reloading and was told that they had lots of preformed brass and would sell it to me. Long story short, I bought 1000 rounds of sized, decapped brass for .02 a round. Problem solved.
  I'm pretty sure the gun range is still in operation, I'll go look it up and post the name on another post.

Hey Floyd! I shoot 7mm TCU in both rifle and pistol. It is a supremely accurate cartridge. You have to make your own cases for it. Yes, it is classed as a wildcat. Why do I do it? because I like the superb accuracy and low recoil. There are lots of us wildcatters out there. Its kind of like asking why would you change the caliber of an M1 carbine when the original caliber is so much fun. 

There were multiple examples of the "Hey, let's neck down a .30 Carbine cartridge to .22!" back in the day.  So a chamber cast and a bore measurement would be in order. The Col. Melvin M Johnson, designer of the 1941 Johnson Rifle, and Johnson LMG - both used by the Para-Marines in the Pacific theatre, as well as by the joint US/Canadian Special missions unit in the European theatre - tried to interest the US Military in the concept in the late 1950's but he was always there at the wrong time since the M16 was already in full scale development, and he had already in 1939 & 1940 "injured" any goodwill with the armament "Powers that Be" by being so pushy about his Rifle as the Garand was in final adoption and about to be mass produced.  He did set up production for his cartridge called the "5.7 MMJ", as well as for his "Spitfire" Rifle and Carbine in the late 1950's and early 1960's, and built a bunch.  As well as having many Spitfire Carbines manufactured by his company Johnson Automatics and Plainfield for commercial sale.  He had originally proposed and marketed conversions by boring out the .30 Carbine barrel, relining with a .224 cal. insert, and brazing or welding in an appropriate for the caliber feed ramp.  Loads are very close to a moderate .22 Hornet load, with a 40 grain bullet pushing 3000 fps.  I have 1 original Johnson manufactured rifle and 2 Plainfield's in the 5.7 MMJ caliber.  But for some reason the cartridge has become commonly known as the .22 Spitfire instead of it's correct nomenclature of 5.7 MMJ, which in a way dismisses the designer.  Wouldn't want to do that to P.O. Ackley...

Edited by smaugmra - Jul 16 2023 at 5:52am

If I could find a decent 22 barrel for a good price, I would be very tempted to go for a 5.7 x 28 conversion. The action is long enough and the pressure is a tad high, but under proof load pressures. I know a guy that could sleeve the chamber and ream it for 5.7 x 28. This cartridge appears to be the one chosen for future replacement of the 9mm as a standard military round and the ammo is available as more weapons are hitting the civilian market. 

I have built a few conversions, but stick with readily available barrels. Unless one could come across a 5.7 Johnson barrel at a good price, $$$ shoots this project down pretty quickly. Chambers can be inserted and reamed for 5.7x28. There again, you need a friend with the tools or it quickly becomes cost prohibitive again. I have used .223/5.56 cases to build Tokarev and fired hundreds of rounds thru that chamber, which is 9mm. I have not looked real close to the difference in brass diameter between a 30-carbine and a 5.7x28. Feeding issues might have to be solved the way they did it with the Johnson. I have had to work out magazine issues with conversions before and am sure that could be overcome.