Joe, The WRA 9M-M headstamp is basically from 1939 to 1945. The The initial contract was from Finland around the time of the Winter War with the Soviets, but that contract was cancelled before delivery. Sweden bought the ammo, but it was still in storage in the US when the British decided they were desperately needed 9mmP ammo after Dunkirk. The British bought the ex-Finnish ammo, perhaps through WRA, and contracted with WRA for additional 9mmP production. This was the RN cartridges that were patterned on the Finnish 9mm production, which was the first large scale production of 115gr bullet 9mmP by WRA, and probably in the entire USA. It appears that Finland introduced the 115gr 9mmP load in the early 1930s for their Suomi M31 SMG. WRA made a batch in 1934 for someone in South America, probably for Bolivia for use in Suomi SMG. In 1939 they also made a contract for Mexico, again probably for Suomi SMGs.
Italy introduced a 115gr load for their Beretta M38 MP. I have no evidence if this was independent or if they were guided in this by the Finnish experience.
The British wrote their first Specification for their standard Sten 9mmP cartridge in early 1941 and it was 115gr, undoubtedly because the 115gr blt was already essentially their standard based on the ammo from WRA. WRA also supplied 9mmP ammo to US forces and probably other governments during WWII.
The 125gr truncated load with the WRA 9 M-M headstamp is interesting. These show up in the early WRA blue boxes from the early 1930, but are dated 1940, years after WRA moved to their Blue and Yellow boxes for 9mmP. In addition the boxes have a D prefix which also shows up on an early White WRA box for the British. This same Blue box, with the same first two letters of the date code “D8” but wrapped in brown paper, heavily waxed, with a Dutch label came out of Indonesia. These were probably a purchase by the Dutch purchasing commission in the US for their forces in the Dutch East Indies. The Germans invaded Holland in May 1940 and this ammunition was packed in Aug 1940.
I suspect there is a lot we don’t know about the Winchester production during WWII and who used their 9mmP ammo.
Tony Edwards has turned up info that the British also bought ammunition from Remington during early WWII, but no ammunition has turned up that gives any indication it may be part of this contract.The indication may be as subtle as a prefix on the load code, but any Dogbone box with an interesting or unusual marking would be a candidate.