My neighboors are Nurses, and one has it bad, he is now on dissability, but had the implant instlled from the brain down the neck into the vertibre. The unit is internal and the controller is in his hip. If you ever watch "Ray Donovan", the TV show, it's the same thing Terry got in the show. Tim, "my neihghboor moved back to Indiana last month, because all of his family including the Doctor he trusts are back there. He was travelling 3 hours here in South Fl, to get an adjustment. They hook another controller onto it magnetically and can dial down the shakes.
It won't last forever, but usually Parkinsons patients don't either, especially at 60 yrs old. He got it a few yrs ago, and this really enabled him to a fairly normal life, as far as driving eating etc, he was shaking so bad, he had given all his hobbies up.
The first thing he did was to buy a new Corvette, said "once more before I go" it's sad, but that's the way my year has gone, lost a friend of 55 years during the last hurricane, Cops found him dead in front of the TV, I called for a welfare Check. And my 96 yr old mother has full blown Dimentia, came on in less than 3 months, and within a year she doesn't know anything anymore. But this I can accept as she did get over 90 yrs of good healthy life.
Shooting would be very dangerous as this progresses unless he gets the implant, I know it's about 100 thousand dollars, but good insurance will cover most of it. When these shakes get bad, there is no way you should be holding a firearm.
One thing to know is that the surgery is not reversable, they drill into the skull, but it works and the shakes go away, the problem is, like anything else the body adjusts, and they have to keep fine tuning it, and at some point it will no longer function. But even if you get 10-12 years it is worth it, because by then, who knows what they can do.