Over the past ten years, I've worked with literally thousands of women as they learned to shoot at a professional firearms training school. To this day, I have literally never met a healthy adult woman who could not be taught how to rack the slide on a semi-auto with less than an hour on the range -- and 99.99999% of those took less than 5 minutes to learn the simple, strength enhancing technique that makes racking the slide an easy no-effort thing. Racking the slide is almost entirely a matter of technique, not strength.
In contrast to this, I have met dozens of women who did not have the hand strength to reliably pull the trigger on a double action revolver for more than a few rounds. This does not matter for self-defense, of course -- unless it does! -- but it makes regular practice nearly impossible. The tricks you can use to make pulling the trigger less difficult for someone with low hand strength nearly all require you to do something contra-indicated in a self defense situation, such as cocking the hammer (decidedly slower, more finicky when the incident is over and your hands are shaking) or using two fingers on the trigger (you may not have two hands available to use). You can adjust where your hand rides on the gun to increase your leverage, but that has limited effects. You can mechanically lighten the trigger pull weight, but that often comes at the expense of the gun's reliability. And that's about it for technique adjustments available to the revolver. What this means is that pulling the DA trigger is almost entirely a matter of hand strength, with very few reliable technique tricks that make the job easier.
Not only so, but many women discover that the super small lightweight revolvers often recommended specifically for women are among the most difficult and least comfortable guns to shoot. Slightly larger guns tend to be much more comfortable for most shooters, which means shooters who start on a slightly larger gun will more likely get the practice they need in order to build reliable self-defense skills.
Related to this, whenever you take a revolver and compare it to a semi-auto within a similar size and weight class, you'll find that the semi-auto almost invariably provides less perceived recoil to strike with the same energy effect on target; that's because the motion of the slide does absorb some of the rearward energy as the shot fires. That absorbed energy gives the shooter a slightly more comfortable experience -- again making it easier and more likely that the shooter will practice enough with the defense gun.
With these factors in mind, my experience has been that it's much more difficult to teach a new shooter to shoot well with a revolver than it is to teach a new shooter to easily and reliably run a semi-auto. There are specific skill sets unique to each type of weapon, but the challenges with a semi-auto nearly all fall within the "easy to fix with the right technique" category, while those with the revolver seem to be endemic to the weapon.
Also, this needs to be repeated for truth!
Women are just as capable of learning the operations of handguns as men. Stance, grip, trigger control are the same regardless of how your undies are shaped. You will do her the most good if you sit down and talk over the relative merits of revolvers and pistols, and do at least as much listening as talking while you do.
If your preference for teaching with a specific weapon type is built around low expectations for your student -- "It's okay, honey,
you won't have to learn anything..." -- that's probably not going to lead to good results in the long run. You will get your best results going in with the expectation that
of course this healthy adult person will be able to learn anything about the gun that she wants to learn!
FWIW.
pax
Edited to add: If she prefers a revolver and can easily run it, that's a different kettle of fish. I'm talking here specifically about the idea that everyone
must learn on a revolver first -- or that revolvers are ideal specifically for women. It's the one-size-fits-all approach I'm against, not so much against either of the main choices. With caveats, the motivation provided by using the gun a new shooter
wants to learn how to shoot often trumps any specific positive or negative factors of the weapon itself.
