Help me ID this pistol cartridge

[fed168]

I received a bag of old ammo, old to the point it is not shootable, but one stuck out. It is FMJ, and the headstamp is WRA CO 38 A.C.
I assume the WRA stands for Winchester Repeating Arms Co, but I am not sure.
The case is rimmed the case is not straight walled, instead tapered at the bottom towards the rim, much like an auto cartridge.
Help?

 

[Mike Irwin]

It's a .38 Auto Colt, also known as a .38 ACP.

Browning introduced it, I believe, in his Model 1900 semi-auto pistol.

The same cartridge was later loaded to higher power levels and became the .38 Super.

 

[fed168]

Thanks much Mike