Things I am assuming;
She can exercise trigger finger control, as evidenced by her son giving her a Shield to begin with.
A larger semi auto will be easier for her to shoot accurately while under duress.
By the time she runs out of bullets with a 17 shot semi, she would have had to "drop the bullets in the hole" two times after the initial 5 shots missed.
She will not have a jam or a misfire in the first five shots from said semi auto.
The issue with a home invader will be resolved one way or another before she has to work the slide, or switch mags.
When she goes to the range she will not be alone, and her companion (her son) will help her with the slide.
Things I am not assuming:
That the adrenaline rush will enable her arthritic finger to operate a double action trigger with the precision necessary to neutralize the threat inside of 5 shots.
That same adrenaline rush will subside so that she can drop more bullets in the holes while the invader is still upright.
Your magazine subscription analogy is just plain silly. To be analogous, the woman would have to be unable to operate either firearm.
There is value in independence without a doubt. Ideally she could do it all for herself. But she can't, so give her the easiest handgun possible to shoot accurately, and one which does the most to offset her deficiencies in hand strength. Protection first, independence second.
We do agree on one thing: if she does go with a revolver, get one with as much heft as she can handle, such as the model 10 you suggest.
