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I was thinking about a way to make a .30 carbine "rifle" more effective, and thought.... 'What if you necked down a .30 carbine case to accept a .223 bullet and used a powder appropriate for the M1 Carbine barrel length to achieve more than the 1900fps of the .30 cal. and still use the same action and mags, just a new barrel of course. Has it, could it, would it be worth the trouble?
 

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That's been done, a lot. I used to be a wildcatter, and collected wildcat cartridges, and I've lost track of how many of those 22 Carbine wildcats there were. At least a couple of them reached semi-commercial status including commercially available carbines.

In that tiny 30 Carbine case, there is not much that can be done, so they all look pretty much the same.

In the wide wide world of wildcats, there is not much that has not already been tried, more than once.

Ray
 

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The 5.7 MMJ has the advantage of using standard magazines and not requiring mods to gas system. BUT - performance ain't all that wonderful, though as Frank Barnes notes, it is efficient. 40 grain HP with 14 grains of 4227 makes 2850 fps; 40 grain HP with 12 grains of 2400 gets 3000 fps; 50 grain HP with 14 grains of 4198 makes 2700 fps.

So - been tried, works, but not so well as to become a popular thing, factory or wildcat. In a carbine, it throws brass all over hell's half-acre, so it tends to be expensive to shoot due to brass loss. I have thought it ought to work well as a conversion in a Ruger 22/77H, what with the rim diameter on the Carbine case being almost exactly the same as a Hornet. Might need a little rotor alteration on the magazine because the case body is fatter, but not that much. Never had enough money to play with the idea.
 

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Instead of necking it down it would have been better with a saboted .223 bullet in a standard 30 carbine case. At the same pressure it has more area to work on and would deliver a higher velocity. The sabots are available so you might try that.
 

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Instead of necking it down it would have been better with a saboted .223 bullet in a standard 30 carbine case. At the same pressure it has more area to work on and would deliver a higher velocity. The sabots are available so you might try that.
+1 on that. By not necking down the case you will likely have better case capacity and better ballistic specs.
 

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On the flip side, by using a sabot you will have a cartridge that will be like all other saboted cartridges - lacking any sort of acceptable accuracy. Small caliber, sporting cartridge sabots have been tried over and over for for many years. The results are usually the same.
 

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If you want to enhance the M1 Carbine, just buy a mini 14 Ruger in 5.56 and be done with it.

If you want to enhance again, then drop the mini 14 and get a M1a Springfield.

The M1 Carbine is as good as the design will get. Its a carbine, not a rifle. Its purpose built
for .30 M1 carbine caliber ammo. You get nothing making this wheel into a square.
 

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If you want to enhance the M1 Carbine, just buy a mini 14 Ruger in 5.56 and be done with it.

If you want to enhance again, then drop the mini 14 and get a M1a Springfield.

The M1 Carbine is as good as the design will get. Its a carbine, not a rifle. Its purpose built
for .30 M1 carbine caliber ammo. You get nothing making this wheel into a square.
+1, agreed.
 

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The M1 Carbine is as good as the design will get. Its a carbine, not a rifle. Its purpose built
for .30 M1 carbine caliber ammo. You get nothing making this wheel into a square.
Indeed so - the whole design is so integrated for getting high reliability from the designed cartridge that it doesn't respond well to any alterations or changes. That includes the pressure at the gas port and the curve in the barrel (duration) and volume of gas into the expansion chamber for that tappet gas piston design. Which works fine - for whatever cartridge it was designed around.

Got to admit, if anyone successfully got a Carbine to take 300 Whisper or 300 Shadow, I'd be interested
I think you could do that - but not as a conversion. Need to be a new-build with modifications to use the pressure and pressure curve of the mentioned rounds. Plus - might have to scale the whole action up a bit because they are a fatter case than the carbine. There isn't a lot of room to put a bigger head and case diameter into the platform. Be very expensive, and (little as I like them) probably better on an AR platform. Maybe (at least) modernized with a gas piston instead of direct impingement.
 
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