The 9mm Win Mag was announced in 1979 along with notables 45 Win Mag and the 375 Winchester. But Brass and Ammo for the 9mm Win Mag was extremely scarce in public hands for some 20 years maybe.
A side note to the 9mm Win Mag history is that on a trip to Great Western in 1989 or 1990 I was visiting with one of the new managers of Iver Johnson/AMAC, we will call him “Neal”. He was bouncing ideas off me to improve the company product line. They had just come out with the 338 Lapua rifle as I remember in 1988. I told him that he should chamber the rifle in 9mm Win Mag. He was very skeptical that the round would be a good idea. I actually was traveling with a couple 9mm Win Mag show rounds. I showed him that they would fit and cycle in a carbine mag and action. ( He refused to let me have them back and they were a $25 dollar round I think at the time. ) Over the course of the weekend I made the idea sound tempting. This was a bit easier since they had 9mm para barrels in stock from an attempt at marketing the carbine in that chambering. We discussed pressures and were only a tiny bit concerned that the “set-back” of this high pressure round would be a bit much for the carbine locking ears on the bolt.
A couple months later I received a handwritten letter discussing the success of the tests and a couple bags of fired proof and standard cases. The gas-port vent diameter was his main challenge. Winchester was happy to have a project that would finally take advantage of their design ( ten years after the development ). He said the diameter was set, and that he had fired 20 proof rounds through his test gun to prove to himself that it would work.
When I saw him shortly thereafter in Tulsa, he agreed to let me have the first ten off the line, five of which were going to be e-nickled and special serial numbers.
Sadly the project was discarded when “Neal” was removed from the company. It was so close to production and could have a pretty good comerical success.
One other thought on the 9mm Win Mag Canadian, I once had some LC basic cases for the 223, that if trimmed would have made a great “display” 9mm Win Mag case. I wonder if someone else had that thought when the 9mm Win Mag brass was not available.