Ramp-down isn’t really possible. The idea behind the super cooled coil is that once activated, it takes almost zero energy to maintain the (very strong, like 300,000x more than Earth’s) magnetic field. A super cooled coil can keep an electric current for a very, very long time. The magnet is ALWAYS ON, and the door into the room has a big warning about it. All employees in the same building as the MRI should be trained to Read The Fucking Sign. Cop should have, too.
It would take a huge amount of force to pry the gun free. I would argue the risk of prying the gun free and it discharging is much worse than the cost to reactivate the magnet. If the gun was hot, I don’t know if they could have even cleared the magazine at that point. The bolt or magazine may have been stuck in place.
During the very early days of COVID I walked into the magnet room with a homemade reusable mask. It had a twist tie in the nose to keep it from fogging my glasses. I was 10 feet away from the magnet when I felt it start to be pulled free from my face. I’ve never noped out of a room more quickly in my life…
Strangely, was never an issue for me. I usually wear thick rimmed plastic ones, the metal in the screws was never pulled into the machine.
But, if I was getting an MRI of my head I would take them off. Mostly because they didn’t fit. But they could also distort the images or, worst case scenario, absorb the radio waves and heat up.