Threading a cap on is exactly what Mossberg did to make a Canada models and would do the same on the 940. Have you physically seen an extended mag model in the store or are you going based on what you see online? Most online retailers selling a JM pro series will show a stock image with the mag extension, but it will be detailed in the notes that the gun is actually a 1+5 not a 1+9. Here is an example
https://selectshootingsupplies.com/930-jm-pro-series-autoloaders/
If you placed an order, you likely would not have received it. Mossberg putting a wooden plug in the gun that could be removed by simply unthreading a mag cap is not the permanent alteration required by Canadian regs regarding centerfire semi’s.
I know personally of someone that bought one plugged. I’ve held it in my own hands. But I guess I wasn’t there to watch him purchase
Regardless, Mossberg will simply offer a “Canada” version.


















































