I have killed many deer myself with the .22 mag
I will tell you where and how,they were legal.
West Virginia,the how is that the DNR issues garden and crop damage permits to landowners for enough deer to stop the damage and compensate for the damages.
This is usually in the summer and you can use anything you want to shoot the permit deer.
I helped a friend shoot 15 a few years back,we shot 2-3 per evening as we saved the meat and that was all we could take care of before they could spoil.
All were one shot kills in the head or neck at 30-50 yds.
when used properly they will certainly do the job,that is why they are the gun of choice for poachers.

The point I was getting across was that the instructers did not advise anyone to deer hunt with .22 mags.