Ray, Here’s an excerpt from HWS Vol III, Chapter 6 which I just happened to be working on:
“There was actually no official designation assigned to the first cartridge case design for the T65 ball cartridge. The Frankford Arsenal drawing of this case was FB 22743 dated 26 September 1946, which was redrawn from sketch BLX-E2-219 dated Jan. 24, 1945, and was based on the commercial .300 Savage case made with the same head as the Cal. .30 service case, and with body taper held to a minimum to obtain maximum powder space.
The case drawing was entitled Case, Cartridge, Light Rifle, Cal. .30, but it was frequently referred to by the Ordnance Department and Frankford Arsenal as the “T65 Case.” The case was originally made with an overall length of 1.871 in., a head diameter of 0.473 in., a rather sharp shoulder angle of 60 degrees, and a noticeably short neck. The shoulder diameter was .450 -.006 in. and the case length was 1.871 -.015 in.
The first armor-piercing (AP) cartridge with the T65 case was the T90, assigned by the Ordnance Committee on July 7, 1945. This round was essentially the T65 case loaded with a Cal. .30 M2 AP bullet. However, testing at Frankford Arsenal in the summer of 1945 disclosed that the velocity of this loading with the heavy (168 grs.) bullet was only 2,500 fps without exceeding the chamber pressure limits established. When the T90 cartridge failed to reach the desired velocity, an AP cartridge designated the T93 was approved for development. The T93 had a 140-gr. bullet and was loaded to a velocity of 2,700 fps. Because of other priorities, work on the T93 cartridge was suspended in December 1945 until the new light rifle being developed by Springfield Armory could be made available for testing. Later, in 1948, the T93 designation was reassigned to a Cal. .30 light rifle AP cartridge using the FAT1E1 case.”
Interesting that the weight of the M2 AP bullet given here is 168 grains, but yours is 163 grains. There’s nothing about your dark wine-red base and bullet, but they remind me of commercial proof markings. Do your case dimensions match the ones listed here?