5.7 Johnson and M1 Carbine

[eb in oregon]

I just found this forum yesterday when searching 5.7 Johnson (5.7 MMJ and .22 Spitfire) and found the thread below fascinating. However it was requested I not revive a thread years old. So here is a new one regarding the same subject.

First, the 5.7 MMJ was designed by Melvin Johnson for a 40 grain bullet, 50 grain maximum. The 30 Carbine case is just a bit small to get the full potential from a 55 grain bullet. It was loaded originally with 12.5 grains of 4227 powder, 40 grain soft nosed bullet (.22 Hornet), to about 2800 fps, with a 1/16 twist. This information comes from Ed Johnson, Melvin's youngest son, and who actually tried to bring that project to fruition after Melvin died. He can be found on "The Johnson Rifle Site" as the sites originator and owner. Ed has stated that they made right around 200 original Johnson Carbines and they actually sold at a loss in order to get the business going. I load the cartridge myself and use either 35 or 40 grain bullets with a charge of 12 grains of H110 for the two and it does pretty well for accuracy and it is a hot little cartridge that is hands over fist better than the FN 5.7x28 and if used in an M2 Carbine is an awesome package.

To build a 5.7 Johnson carbine you need a barrel (made by several different business's after Johnson's company folded due to lack of orders) and to re-profile the feed ramp for the cartridge. The feed ramp is the tricky part as I've never seen a drawing or a decent description of how that's done. Plainfield Machine made some later, as did Iver Johnson, IAI, and Fulton Armory. Unfortunately it never generated enough interest when those company's were making those carbines and that's a shame as it is a tremendous cartridge for the platform it was designed for. Of the carbines manufactured for the 5.7 Johnson obviously the original carbines are the best to have but they are getting as rare as fangs on a chicken. I've heard the Fulton Armory carbines were of good quality but have never seen one. The IAI and Iver Johnson had quality problems, which is the primary reason they weren't so successful. I've an original Johnson and an IAI carbine, the Johnson is of a higher quality though it used an aluminum cast trigger housing that Ed Johnson sourced from Plainfield Machine. It was due to the collapse of Johnson that Plainfield even started making M1 Carbines in the first place. A stock of unsold parts destined for others.

It has been claimed that the government bought some Plainfield carbines for use by security contractors, however I find that hard to believe as the federal government has huge stocks of M1 Carbines in storage and has been receiving them back for years from foreign country's that were given some later, it makes little sense to buy more from an upstart and new company. I don't know how some of those receivers ended up at the CMP but they were never in service with our military. Anyway, the 5.7 Johnson is a good cartridge and it's performance is greater than it's size and weight.

https://www.milsurps.com/newreply.ph...reply&p=266241

https://www.johnsonautomatics.com/

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