M1 Carbine in an intermediate caliber

[eb in oregon]

The specs on the .30 carbine was approx. 1900 fps. max effective range was 300 yards with a velosity of about 850 fps. The same as a standard .38 spl round. After 300 yards it began to loose everything. When Johnson converted carbines over to .22 cal. the best he could get with proper pressure guildlines was a light weight 40gr. bullet at 2800 fps. The US military was looking at .22 cal. rounds at that time and other rounds with a hevier bullet and higher velosity were already being studied. As someone else said he was a little too late to the party.

Yet now the 5.7x28 is considered "good enough" but the 5.7MMJ (.22 Spitfire) is far superior.

[RCS]

There was a 30 Kurz cartridge developed for M1 carbine conversions longtime ago, believe an article in
one of the 60's or 70's gun magazines. They used a 308 Win cartridge case shortened to 33 mm and
necked for 308 diameter jacket bullets. I had a friend that started building one of these "kurz" carbines.
He had the bolt face opened-up to and a special longer 30 cal barrel with the gas system moved up a
short distance. this barrel was chambered for the 7,62x33 cartridge which just fits inside a carbine mag-
azine with short bullets. I did not help him with this project as I felt it was not safe, do not know if
he shot this weapon, I do have a sample dummy 30 Kurz cartridge from this project

[floydthecat]

If it ain’t broke don’t fix it.

Carbines can certainly be converted and I have done that myself, but not to attempt to improve 7.62 x 33 performance. Too many other rifles out there chambered in about anything one could desire.

[RCS]

While a little off the main subject, and on another website, there a person who used an 7,92 mm barrel chambered for
7,92x33 Kurz on a M16 barrel breech. It was installed in a AR-15 upper with a 308 (.474 dia) bolt. only 7,92 mm bullets
were 125 gr. While accuracy was not really good, the magazine only could function with three or four cartridges, he never
could get a larger capacity magazine to work. A very expensive project with 7,92mm chamber reamers, headspace gage
and making the barrel

[browningautorifle]

accuracy was not really good

I'll bet it was either his twist or inside barrel diameter. Simple...

[mrclark303]

Thanks all for your feedback, some very interesting observations as we have all come to expect from our community.

I find all these various wildcat cartridge experiments very interesting..

RCS, you were certainly right to be concerned with a .30 Kurtz type cartridge, an interesting concept that might find a suitable rifle in a converted Mini14.

I would also have grave concerns regarding firing such a round from an M1 Carbine reciver.

Tied to a tree perhaps, with a length of string!

[RCS]

Going back to Mr Clark's original question concerning US Ordnance and the 7,92x33 cartridge, to my knowledge nothing was tested
or any cartridge variations were tested. While the Soviet's had knowledge of the weapon and cartridge as early as April 1942 from
battlefield experience, they realized the concept of an assault rifle and intermediate cartridge. The US continued with the 300 Savage
and worked up to the 7,62x51mm while ignoring the excellent 7x49 Liviano sold to Venezuela (remember the 276 Pedersen)

Some years ago, I had the chance to examine an original German MKB 42H and was quite impressed by the design, heavy yes and
fired full auto from an open bolt, but this was available in 1942 !

[Wineman]

There is no problem firing a "full size" rifle round full auto. Just have enough mass to compensate: BAR, BREN, FG42 etc. Full auto has it's merits but even the M16 is not as accurate as when firing slower and probably does not have the build to be a machine gun (see SAW). Heads down yes, effective, not so sure.

Dave

[M94/14]

There is no problem firing a "full size" rifle round full auto. Just have enough mass to compensate: BAR, BREN, FG42 etc. Full auto has it's merits but even the M16 is not as accurate as when firing slower and probably does not have the build to be a machine gun (see SAW). Heads down yes, effective, not so sure.

Dave

Yes, even the LMG version of the M-16 had limited success in Vietnam. Not until the M-249 came around about a decade and a half later did they get a reasonably lightweight platform that functioned well and was controlable, albeit belt fed.

The biggest problem with most of the many cartridge variants that M1 carbines had been converted to over the years, was finding one that actually provided a ballistic advantage over the .30 carbine round while confined to the Carbines 40,000 cup max operating pressure. Very few cartridges performed better within this limitation when compared to the M1 Carbines original performance requirements.

[eb in oregon]

There is no problem firing a "full size" rifle round full auto. Just have enough mass to compensate: BAR, BREN, FG42 etc. Full auto has it's merits but even the M16 is not as accurate as when firing slower and probably does not have the build to be a machine gun (see SAW). Heads down yes, effective, not so sure.

Dave

Actually keeping their "heads down" while the grenadier or a fire team flanks the position is usually rather "effective."