M1/Ballistics on the .276/.256

[eclancy]

Hi all,
Well you guys wanted an easy one so here it is:
During testing in the later 1920's Ordnance was looking for the new semi-automatic rifle to be in a .276 caliber, but look wait, Ordnance also was looking for the new semi-automatic rifle to be in a .256 caliber. My qustion is what was the Ballistics to be between the .276 cal. and the .256 cal. for the M1 Garand rifle? Have fun
http://www.garandm1rifle.com
http://www.users.fast.net/~eclancy
Thanks again for taking the time and effort to read and reply to this.
Clancy

 

[Barry in IN]

Good one, because although I knew of the .276, I didn't recall anything about a .256.
That is, until I cracked open "Hatcher's Book of the Garand", and read the "Pig Board Tests", and there it was. I remember reading that a few times and being curious, but it didn't stick with me.

Anyway-
The .276 used a 125 grain bullet at 2700 FPS- generally.
I see the bullet was tested in flat base, and boat tail configurations. Evidently there was some experimenting done with 140 grain bullets. It was basically said that, if going up to a 140 grain bullet (2600 fps), they may as well use a 140 grain bullet in the .30-06.

The Pig Board Test results summary states-
"At 300 yards, the caliber .256, 125 grain flat base bullet gave by far the most severe wounds in all parts of the animal. All calibers caused very severe trauma, but the .256 seemed to be in a class by itself. Next to the caliber .256 the caliber .276 flat base bullet must be considered as occupying second place."

So, I have the .256 as using a 125 grain flat base bullet, but can't find a velocity figure- yet.

 

[Alfadog]

Interesting that 75 years later, we're looking at the 6.8mm SPC with practically identical ballistics (115 gr. at 2650-2800 fps).

 

[Tony Williams]

You need a copy of 'Assault Rifle: the Development of the Modern Military Rifle and its Ammunition' - see my website for details

This is an extract:

"There had been some official efforts towards considering intermediate calibres, with the US Ordnance Department in the late 1920s sponsoring comparative trials of the effectiveness of different rifle cartridges using anaesthetised pigs and goats to assess wounding effectiveness. They concentrated on a .25 inch (6.35 mm) – a rimmed ballistic test round firing an 8.1 g bullet at 808 m/s (125 grain at 2,650 fps) – a .276 (7 x 51) and the existing .30-06 (7.62 x 63) rifle / MG round. The .25 most impressed the testers, but the Department chose the Garand rifle chambered for the .276 Pedersen cartridge which would have made an effective assault rifle round."

In fact, the test .25 was reportedly based on the 8mm Lebel - a curious choice!

Tony Williams: Military gun and ammunition website and Discussion forum

 

[Daniel Watters]

You need a copy of 'Assault Rifle: the Development of the Modern Military Rifle and its Ammunition' - see my website for details

This is an extract:

"There had been some official efforts towards considering intermediate calibres, with the US Ordnance Department in the late 1920s sponsoring comparative trials of the effectiveness of different rifle cartridges using anaesthetised pigs and goats to assess wounding effectiveness. They concentrated on a .25 inch (6.35 mm) – a rimmed ballistic test round firing an 8.1 g bullet at 808 m/s (125 grain at 2,650 fps) – a .276 (7 x 51) and the existing .30-06 (7.62 x 63) rifle / MG round. The .25 most impressed the testers, but the Department chose the Garand rifle chambered for the .276 Pedersen cartridge which would have made an effective assault rifle round."

In fact, the test .25 was reportedly based on the 8mm Lebel - a curious choice!

According to my sources, there were several different .256 (actual diameter .264") rounds tried. An early one was indeed inspired by the Lebel case. This was primarily tested with 140gr bullets at 2,600-2,750fps per the original Ordnance recommendations. However, later test cartridges used .30'06 cases, both full length and shortened. The Pig Boards used one of the shortened variants with a 2.199" long case loaded to your quoted specifications: 125gr at 2,650fps. You can find drawings and specifications in History of Modern US Military Small Arms Ammunition: Vol. I.

 

[Tony Williams]

Curiously, my information on the .25 cartridge comes from Bill Woodin of the Woodin Laboratory - one of the authors of that book!

TW

 

[Daniel Watters]

Curiously, my information on the .25 cartridge comes from Bill Woodin of the Woodin Laboratory - one of the authors of that book!

What can I say? It was in their latest revised edition, and wasn't updated in their 2002 Addendum.

 

[eclancy]

Hi all,
You guys are all around it, but not there yet. All I have to go by is the Ordnance files from the War Dept. If you bought a copy of one of my books I think at that point in time SA was ready to attack the War Dept. Good going at least you guys are getting into this quiz. Have fun and keep up the good work.
http://www.garandm1rifle.com
http://www.users.fast.net/~eclancy
Thanks again for taking the time and effort to read and reply to this.
Clancy
ps But then again what do I know

 

[eclancy]

Hi all,
The answer to this quiz is as follow:
Ordnance Technical Staff
Dec. 1, 1927
Items 5601-6375 OCM
Bullet flat base
Gilding Metal Jacket, Weight 140 grains
Powder Charge Sufficent of a Suitable Military Powder
to give a Muzzle Velocity of 2600 fs.
This was the data for both rounds
One of the Ordnance Officers signed is Capt. James L. Hatcher
http://www.garandm1rifle.com
http://www.users.fast.net/~eclancy
Thanks again for taking the time and effort to read and reply to this.
Clancy