Ah - the plot thickens. The full story is that the Cdn War Museum (where I volunteer) is being offered a 40-mm bofors casing with the markings (on email, no photo) "40-mm M25 lot 1217, manufactured in 1944, MR/C". The offerer says that it belonged to his mother who was a supervisor at Pedders in WW2 and "made lots of them".
We have asked for a photo but the firm Pedders is not familiar to me although it could have been a subcontractor manufacturing casings for the 40mm. Canada produced more than 12.5 million rounds of 40-mm ammunition during the war.
Thanks for the reply. Obviously more digging required on my part. The museum has lots of 40-mm casings, what makes this one unusual is the purported provenance to a minor Canadian (maybe???) producer.
doug