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Got a comment suggesting that M1 Carbine ammo in Korea wasn't up to snuff.
I can't find the information they're citing, but the looking for it did turn up some interesting stuff about cold weather and ammo performance.
An Army publication for snipers (FM 3-22.10, Sniper (Dec 17) referenced in this link) says the round will impact 1" lower at 100 yards per 20°F the temperature is below the temperature when you zeroed the gun.
FM 3-22.10 pg. 4-147. The change in the point of impact is best determined by referencing past firing recorded in the sniper data book. As a rule of thumb, a 20-degree increase in temperature will raise the point of impact by one minute; conversely, a 20-degree decrease will drop the point of impact by one minute.
And that's with a spitzer shape, not a round nose; like the .30 Carbine!
Chosin was -35°F and if the troops had zeroed on a nice 75°F day there's a 100 degree difference, or a 5" change of impact at 100 yards. 10" at 200. 15" at 300...
That's assuming the cold soak didn't weaken the springs so bad the hammer doesn't hit hard enough to set off the, now, less sensitive primer...
Norma published a video showing that .30-06 lost velocity as it got colder.
Everything is in Godless Metric.
Room temperature average velocity is 2,625 fps.
28°F ammo is 2,575 fps. (1.9% drop)
0°F ammo is 2,532 fps. (3.5% drop)
Norma specifies 2,772 fps. for this round from a 24" barrel, so we're also seeing the effect of losing 2" of barrel in the test.
2,772 gets us the bog-standard 7d pi from .30-06.
2,625 drops it to 7d-1 pi.
2,575 gives 6d+2 pi.
2,532 gives 6d+2 pi.
A 3.5% drop in velocity for an M1 Carbine goes from 1,990 fps. to 1,919.5 fps.
That drops it from 4d+1 pi to 4d pi. Still plenty of energy to penetrate winter clothes.
Losing another 3.5% to get to Chosin temps (baseless extrapolation here) gives 1,850 fps and 4d pi.
With these numbers one cannot help but concur that the troops were missing their targets.
There's a couple of sources that mention the Chinese troops were drugged to the gills. I've written about another case of bad shot placement and drugged up opponents before: Juramentado.
I came across an interesting article a while ago that lays the blame not on the gun, nor the cold but the powder. Seems that the powder used in the Carbine round burned quicker, but Korea quickly went through available ammo and powder and there was a surplus of powder for the .30-06, which burned slower (as it was designed for a full sized rifle.)
ReplyDeleteThus, during the time of the Chosin fight the M1 ammo was a tad weaker than it should have been.
Combine that with Chinese in heavy padded coats while on drugs and it being very cold, well, it's the intersection of a very complex Venn Diagram.
My uncle was a lifer in the U.S. Army. He was in both Korea and Vietnam. The only firefight he was in was in Korea. He told me about the M1 Carbine he was issued.
ReplyDeleteIt seems that they were faced with a human wave of Chinese soldiers coming at them. He said that he shot one Chinese guy wearing a quilted vest at a distance of about 100 yards. He saw the puffs of dust hit the man in the chest 3 times, and the man kept on coming.
That was the only time he said that he was scared during his entire time deployed in a combat situation. Eventually the man fell, but I recall my uncle telling me that most of the opposing soldiers were hopped up on what he said was opium, but it might have been just about anything.
I have read stories about the German troops during WWII also being drugged with Meth during particularly dangerous actions. Whether any of this, both the German soldiers and my uncle's tale are of course not verified, but while my uncle had many neat stories about his time in the service, including having one of my cousins born in Turkey, I tend to believe his story about the M1 Carbine.
As an aside, my uncle was a communications man, so that is why he was issued the carbine. In Vietnam I don't know for sure where he was stationed. But after he retired, he went back to work out of the same office, using the same equipment, paper forms, and chain of "command" as before he retired, but as a civilian contractor, making twice as much money as when he was a military man. He eventually died from exposure to Agent Orange, which gave my Aunt a higher % of pay from his retirement than if he had died of natural causes.
https://thecmp.org/wp-content/uploads/CarbineNotes.pdf
ReplyDeletePage 6 notes performance of usgi 1950's era carbine ammo.
I would never have found that on my own, thanks!
DeleteI wish it included some chrono numbers.
Delete10-in drop at 200 yards indicates 30% slower muzzle velocity, roughly 12 or 1300 ft per second instead of 2000. Add the effects of Sub-Zero temperatures, and you might have a problem.
DeleteSplitting the difference to 1,250 gives 2d+2 pi-, or the same as .30 Super Carry.
Delete7% velocity loss from the cold drops it to 1,163 fps and gives the same damage.
4-14 raw damage with an average of 9 will get 8 through DR 1 winter gear which becomes 4. Need at least three shots to get a consciousness roll on the torso and five to get to a death roll. A single shot to the vitals, will get that death roll as well.
Out past the 1/2 range it gets pathetic. 2-7 with an average of 4. 3 will penetrate the winter coat and be reduced to a single point of damage it will then take at 10 (TEN!) shots to get to consciousness checks and 20 to make it to a death roll to the torso. Two shots to the vitals gets a consciousness roll and three make it to death roll territory.
So, don't use underpowered .30 Carbine ammo in the BLEEPING cold past 330 yards!