Request input on cartridge case formed from the 30-06 Springfield case

[hpshooter]

A friend was gifted a good number of '06 cases from the estate of an elderly shooter and reloader. Mixed in the regular WWII vintage cases were a few cases that had either been Wildcatted or converted to a yet unidentified standard cartridge.

The head-stamp on the case I have measured is RA 43. I only mention this because it tends to make me believe that this conversion was most likely done in the late 40's early 50's time frame. The following measurements are taken from a fired case:
Fired Case length 2.265"
Fired Neck OD .341
Fired Neck ID .311
Neck Length .312
Dia. At Shoulder .435
Shoulder Angle Appears to be the same as on the 6.5x47 Lapua. It is radius-ed at the case sidewall juncture.

I have been through both volumes of Ackleys books and a couple older gunsmithing text and if it is in any of them I have overlooked it. Pretty sure it is a .30 caliber something. Any ideas would be appreciated !

 

[Adam in WI]

Picture?

 

[hpshooter]

Picture?

Will try to get one sent.

AWAG 303 Rifle rechambered to take a 30-06 case necked up to a 303 bullet. Which rifle, my guess 1917

Have some .303 brass to compare it to, didn't think about that possibility.

 

[Adam in WI]

You might have a one-off. The neck is too short to be a Gibbs, which was my first guess

 

[hpshooter]

You might have a one-off. The neck is too short to be a Gibbs, which was my first guess

That was the first cartridge I thought of and compared the dimensions to. Interestingly enough, we have a club member who shoots a .30 Gibbs that his father built when the Gibbs was popular.

 

[jasophil1]

7.7 x58 Japanese

 

[Adam in WI]

7.7 x58 Japanese

Neck is too short to be the Jap

 

[jasophil1]

7.7 Jap has a short neck only thing they used for in 311 that size neck 40 50 .

 

[Tommie]

8mm wildcats based off the ‘06 case were pretty popular post WWII. Lots of 98 Mausers made it back to the USA but 8x57 brass was not common (to say the least). The straight 8mm-06 was a straight forward rechamber job for those those Mausers.

 

[243winxb]

http://www.huntingtons.com/dies_caseform.html#caseform

Mayy be in the list of case forming dies by RCBS?