I was looking through my brother's newest G&A magazine (they come here first and we have to send them to him in college) and found an advertisement for a M-1 Carbine conversion kit. It is a barrel chambered for a 30 Carbine necked down to 22 caliber. They referr to it as a 5.7, now the question. A couple years ago there was a sub-machinegun developed for a 5.7x37 round. No civilian models of this were allowed to be made as the BATF or some dipshit government organization found the cartridge to be "unsporting" in nature. Not that I really want a civilian version of the FN P-90, I was just wanting to know if this 5.7 round for the M-1 Carbine is the same round that the P-90 shoots? And wouldnt it (the 5.7x37) be aweful damn close to the 223 rem or the 222?

David, off the top of my head, I'd think this round would be closer to 222 in ballistics. I hope you are not thinking of such a thing for an M-1 Carbine. Maybe I'm old fashioned, but I think those little rifles ought to be just left the way they were made. I don't know how FUNCTIONALLY good any of the conversions are anyway. But to each his own. Good luck.

Hey, what sucks about Troy, Montana? I'll trade you San Antonio for it any day you like.

That's an oldie, Dave.

Seems to me it dates to the mid-50s. You can find data in Cartridges of the World. Offhand, it is somewhere between a .22 Hornet and .221 Fireball and I can't think of an excuse in the world for it unless you have run out of things to do. (An impulse I have succumbed to a time or three.)

Not likely to be accurate enough to be a good varminter in a carbine.

The 5.7 FN is actually a quite bit smaller than the 222 or the 5.7 Carbine. It is only 28mm long, not 37 so it's even smaller than the 22 Hornet. What makes it so nasty is it's bullet design, it uses a 23grn sharply pointed solid bullet.
Still sounds like a intresting conversion, although I would gather you would have trouble getting it to feed properly.

Dan,
the 5.7 carbine was a factory item (briefly) in the long, long ago. I never heard anything good about it, but I never heard of feeding problems either. I have a very vague memory that it is also known as the 5.7 Johnson.

The Johnson was designed by the same named person,at the behest of the Air Force who was looking for a high speed rifle for air crews.It is a fun little round but hard on brass,I have one that seems to be on perminet loan to buddy to ride on his tractor,to pop hogs with.

I dont have a 30 Carbine, and if I did I sure wouldnt want this conversion. I was just asking if the 5.7 Johnson (that is in fact its name) was the same as the 5.7 FN uses. I guess they are not.

David,

Thank you kindly for bring up a very interesting topic, and I apologize that we have drifted off on a tangent that does not interest you.

The 5.7 FN is an entirely different cartridge. DaveD's post jogged my memory. It seems to have been designed solely to defeat soft body armor. As DaveD noted, it has a very sharply pointed, solid brass bullet at a fairly high velocity. It would go through most soft body armor like wet toilet paper and would anger the occupant considerably. It would have roughly the knockdown power of a well honed icepick.

Just another silly idea, imho.

OH damn, that was great. "...and anger the occupant considerably." Good description.

Unless I'm mistaken, the "outlawed" round was the .22 BOZ, made from a necked down 10mm pistol case. It fell under the "no armor penetrating PISTOL ammo" ban of a couple years back since it was designed for handguns. Fed's handguns. Hmm.

Can't imagine why anyone would want the 5.7 mm M1 Carbine, myself. Just my snidely opinion.

Redial

There are ways around the 224 BOZ, since it is easy to get 10mm brass and have one of the reamer builders makes you a 22-10mm. You could easily convert a rifle for it, but a handgun would be quite a task. However making the a 5.7 FN would be near impossible since it is proprietary brass and bullets.

". However making the a 5.7 FN would be near impossible since it is proprietary brass and bullets."

Difficult? yes. Imposible? No. The brass CAN be found at almost any range where Swat teams may practice with their P-90s. As for bullets...Well the 5.7 actually uses a 0.224 bullet, so it;s easy enough to reload the brass with any good 22 slug.

I know, I have several pieces of brass acquired in this way.

Thats why I said near impossible, I am sure you could probably even find a someone who has a pile of them swept up from the range. Yes the bullets are 22 caliber, but it will be near impossible to find a source of 23grn armor piercers.

The .30 Carbine necked to .224 was called the MMJ 5.7 and also called the .22 Spitfire. Melvin Johnson made a bunch of M1 Carbines for the war effort during the late stages of World War II. They were used mostly in the Pacific theater of the war. When the war ended, Johnson still had a warehouse full of the carbines, but no government customer. He tried variously to sell them to Central and South American countries with mild success. Finally, he tried rebarreling them from plain-jane .30 Carbine to the .224 barrel and marketed the "wildcat" as the MMJ 5.7 in this country. Not a great seller, but a lot of fun to shoot.
The 5.7x28mm P-90 cartridge has been described quite accurately in the above posts. Pure military cartridge and supposedly banned for civilian ownership by the BATF. Although the cartridge is a FN (Belgian) design, they're made in the US in Columbia, SC.
Feeding the adage that there's nothing new under the sun, before the .224 Boz was a glimmer in a wildcatter's eye, there was the .224 Zipperer, a .22 on a .38 ACP case, from the 1950's or 1960's made by Wild Bill Caldwell or it may have been his father. The velocity of that handgun cartridge pretty much equals the Boz.
'puck