Gonna hate myself for chiming in here, but...
My profession is occupational therapy (OT), and in addition to that discipline I am a certified hand therapist (CHT). As such I specialize in rehabilitation of the arm, shoulder and hand. We are frequently confused with physical therapy, since the general public tends to interpret all physical medicine disciplines as physical therapy. We are concerned with all of the occupations of daily living, meaning work, rest and leisure, which is why it's called occupational therapy.
I treat patients with various types of arthritis every day of my working life. Some have had surgery -- including joint replacements -- to address their issues. Some can be treated more conservatively. The essence of my practice with arthritis involves finding ways for my patients to safely continue with activities that are important to them while maintaining strength and range of motion and preventing deformities.
With respect to shooting, it's a repetitive activity involving forceful gripping and, in the case of larger caliber guns, repetitive shock to the joints, large and small. Medications and even home remedies are all fine, and frequently can improve quality of life in general, but it is still necessary to avoid behavior that damages the body.
Here is my (drum roll) professional advice for shooters on the subject of arthritis:
1.
Reduce the force needed to grip the weapon. Get good, ergonomic grips and stocks. Nothing has worked better for me with heavy revolvers than Bill Jordan Trooper grips by Herrett's or Pachmayr. "Coke bottle" type grips also make sense compared to the crappy shapes of S&W target grips of more recent years. Tyler T-grips are good with smaller, skinnier stocks and frames. Larger, softer grips that distribute the recoil into the larger areas of the palm also make sense. Find what works for you. Buy for function, not appearance, as you would a hunting dog.
2.
Reduce the shock of recoil. Have a .22 handgun or rifle as the understudy for your centerfire weapon(s). Dry fire instead of using live ammo. Buy an air rifle/pistol. Use carpenter's type work gloves with a gel insert in the palm and friction pads on the fingers with open finger tips.
3.
Reduce the number of repetitions in the task or activity. Load magazines or speed loaders at home where its warm before you go to the range. Don't reload 500 rounds of pistol ammo and shoot on the same day. Don't swing a 20-ounce hammer with a firm grip all morning and then try to relax with your .44 blaster all afternoon.
4.
Use larger joints to perform the heaviest work, whenever possible. Switch from isoceles to Weaver. That way the shoulders take the load and the wrists and elbows not so much.
5.
Identify the other, non-shooting tasks you do that irritate your joints and find ways to avoid wearing down your joints with those activities. See an occupational therapist in your area to help with this. Try your local hospital or the yellow pages. Ask your primary care provider for a referral. Your health insurance will cover it. OTs call this type of intervention "joint conservation."
5.
Any measure that is designed to reduce repetitive stress that will lead to an overuse injury is doubly important for those with arthritis.
6.
Be aware that every ache and pain you may have may not be from arthritis, even if that is what you have been diagnosed with. The soft tissues of the body will go into spasm to protect (i.e.; "splint") a painful joint. Appropriate strengthening (read that as gentle and sensible exercise), stretching, massage, myofascial release techniques, Kinesio taping, ultrasound, moist surface heat and other physical medicine interventions can all have good success here.
Now, why did I say that I was going to hate myself for chiming in here? 'Cause nobody is going to want to do this. Most of us just want to take a pill or have surgery rather than take active measures to do things better. Sigh.