I'm 76, and thanks to Vietnam and Agent Orange, my back and hips are about toast. VA takes pretty good care of me - three MD's and two Neurologists, plus some Cardio guys (yeah, it got my heart also - blew out the bottom!).
I am OK with about 20 rounds, but greatly prefer firing from the table. And there is no way I can walk out and change targets. I make about 25 yards, and cannot move the hips due to the pain. Got holes in the spinal column, "Myelo Malachia".
Couple weeks ago I fell in TSC, landed with my butt on the corner of a shipping pallet. Upshot was, broke both the coccyx and the sacrum. My new pain doc (VA referral) repaired it surgically, operating mostly robotically (!). Instant relief of that pain, only had two small (.25 cal) holes in my back. I take a few synthetic opoids daily, but the main pain relief is from Gabapentin (Neurontin). That twice a day pill is a miracle worker, believe me.
So, I sit mostly when I shoot. Not too bad, when you get used to it. But, I do have three ML revolvers to shoot, but they are still all 3 virgins.
Started shooting ML's back in 1960 - the smell is apparently about as addictive as some of the stronger illegal drugs!