9MM Automatic?

[Buckshot]

"A straight-walled case dramatically improves cartridge feed angle and feeding reliability."

It's pretty hard to imagine how one could "dramatically" improve the feeding reliability of the 9mm cartridge...

I think that statement is only likely to be true if you are feeding the cartridge thru a straight walled mag with parallel sides (most single column pistol mags). Tapered cartridges thru curved mags have the greatest mechanical advantages for feeding reliability.

[Buckshot]

There was a LOT of caliber changes made by many counties as a result of the lessons learned on the WWII battlefield. The Italians found their 6.5mm rifles inadequate, and were converting to a 7.35mm cartridge. The Japanese found their 6.5mm rifles also inadequate, and were in the process of converting to a 7.7mm cartridge.

While there were forces within both Italian & Japanese ordinance depts that perceived the need to upgun from their 6.5mm cartridges & pushed it through, I've never seem any actual battlefield reports that there were effectiveness issues with their respective 6.5mm weapons. If you can point me in the direction of any such ducumentation, I'd love to get up to speed on it.

[Hauptmann]

While there were forces within both Italian & Japanese ordinance depts that perceived the need to upgun from their 6.5mm cartridges & pushed it through, I've never seem any actual battlefield reports that there were effectiveness issues with their respective 6.5mm weapons. If you can point me in the direction of any such ducumentation, I'd love to get up to speed on it.

I read it years ago in some hard cover military history books. I cannot remember the names. The Italian battle field reports in the north Africa campaign were that soldiers were getting good torso hits on combatants, but the rounds were often failing to stop. Dr. Fackler's work on the 6.5 Carcano demonstrated that the common military load often would not yaw before it exited the body. The Carcano bullet was designed as a low recoil, long range bullet for trench warfare and it lacked the ability to yaw rapidly. As for the Japanese reports, they are less well documented......like all things on the Japanese side. However, there was an effort by the Japanese to retool for the 7.7mm, likely for the same reasons the Italians experienced since the 6.5mm Arisaka had essentially the same bullet design and battlefield purpose.

Arguably the most terminally efficient cartridge of the war was the German 7.92x33mm 123gr FMJ as tested by Dr. Fackler. Of all the WWII cartridges and loads tested, the 8mm Kurz had the spitzer shape that was closest to the ideal tear drop. The tear drop shape facilitates rapid yaw in tissue in FMJ form, and the German MP-44 by testing had the best terminal effects. Most of the cartridges of the war were setup for long range trench warfare, and had delayed upset.....or in the case of the 6.5mm cartridges, they often exited the body and never yawed. The .303 British was probably the second best at rapid yaw.

Here's some info from Dr. Roberts:
https://pistol-forum.com/showthread....listic-History

[Buckshot]

Thanks!