37mm M63 Mod 1

[US-Subs]

Picked up a load of scrap ordnance yesterday, not very much special but I did find one interesting piece. The 37mm M63 is a base fuzed HE round, internal construction is fairly heavy steel, giving it a slight AP capability. In this load, however, I found a cartridge that looked nearly identical but with some key differences. I'm not sure if it is a normal projectile of not. The M63 Mod 1 is identified in documents as a TP round for subcaliber guns used with certain heavy calibers - 90mm and up.
The first difference that I noticed was that the rotating band is different from any of the standard 37mm of this type. The second thing, more surprising, was that while the projectile has the same outer and inner configuration, it is made entirely of brass. This is not mentioned in my references and I have not seen it before. Does anyone know if this is normal?
Photos below of both rounds for comparison.

 

[MINENAZ16]

Nothing for the brass material but a picture with 2 different bands for 37mm M63 mod 1 :

 

[Fred]

The brass projectile might be part of a drill round. I have an American 90mm AP drill round in my collection made entirely of brass.
fred

 

[US-Subs]

I have a number of those as well, but typically they have their own designation, not the model number of a specific munition. Likewise, they are usually all brass and do not contain a copper rotating band or the same internal construction as a service round. This one is a bit confusing.

 

[jeff w]

Can you post everything engraved on the drive band of the brass M63... might offer a clue (lot# year manufacturer code...)? Definitely an oddball.

 

[US-Subs]

I'll try to remember this weekend. Still at work and we've got this latest storm to deal with. About a quarter inch of ice on everything already and it's just starting.

 

[MINENAZ16]

Herewith a 37mm with brass jacket in your archives from Aberdeen. Different (AP) but brass made (external) :

 

[US-Subs]

 

[jeff w]

So yours is lot number GP 13 (Grapho Products, Indianapolis) - coincidentally that is the same maker/lot number on one of the M63 Mod1s MineNaz16 pictured above. But his M63 Mod1 (GP 13) is painted blue and shows signs of rust. Since they both have the same lot number, they were identical when originally manufactured - all constructed on the same line, by the same machines with the same heats of steel, construction techniques etc. That is the rule for lot numbers during the war. Yours must have had a really good brass plating done post production. If you have a really good magnet see if you can get it to stick to some of the steel underneath. Grapho had contracts for shells, projectiles and practice shells during the war.

 

[US-Subs]

Jeff,
as mentioned above, all brass, with the exception of the rotating band. Passed an initial scratch test and no magnetic attraction. LOT numbers are a great guide, but like so many things, what actually happens on the ground is not always by the book.

 

[jeff w]

Wow.
I'd have to guess whoever made yours used a shell from lot GP 1 3 to make the mold for the the brass casting you have.
Just when you think you've seen everything....

 

[jeff w]

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