Unusual cartridge case

[US-Subs]

As part of a large purchase I recently gained a number of fairly unique cases. Here is one that I am not familiar with. It is a US 127mm, T66E3. It has the separate plug in the base for installing powder, typically for the earlier fin-stabilized rounds. In addition it has what appear to be guide rails for said fins. These rails are screwed into place, directly through the case wall. I've curious to what the projectile looked like. Anyone have any information? 127mm is a 5-inch, for those metrically challenged.

 

[Przezdzieblo]

Looks similar to US experimental APFSDS from 1950s-1960s. This at scheme is probably 90 mm. There were some ideas of APFSDS for 5"/38 guns, back in 1956. Do not know if any models were made.

 

[strakv]

It might be for the 127mm Heavy Gun M144 and/or the M155 heavy tank.

 

[HAZORD]

Well, 5 inches is 127mm.

 

[charley777]

Please provide the dimensions of the 127mm T66E3 case in first post.
Length, rim diameter
Thanks very much

 

[Przezdzieblo]

Ok, some new input.

Projectile for that case could look similar to this one seen below, experimental 5/2,5" HEFSDS for 5"/38 gun. It was naval project, based on earlier experiments with 3"/50 gun.

 

[US-Subs]

While I don't doubt that the Navy had a project, I question if it is the same one. I confess I never paid that much attention, but it would seem odd for the Navy to have the case developed at Frankford Arsenal - per the headstamp?

 

[Przezdzieblo]

I have no specific idea. FA was involved in various subcalibre ammunition projects. I can guess that in some cases of ordnance research and development there was cooperation between Naval and Army estabilishments, for the wheel to be not reinvented.

What is inside diameter of the front end of the case? It is said that for 5"/38 HEFSDS the case has to be neck down from 5.31" to 5" to fit projectile's sabot.

 

[US-Subs]

I won't be able to look until this weekend. No time after work, I try to catch up on everything Sat-Sun, but rarely succeed. Send me a reminder Friday or Saturday and I'll try and look.