The issue is what your wife can handle, while respect others opinions, I bought my wife a Lady Smith 38, by Smith & Wesson, she loves it, we live in the country and it has ammo for snake shot too..
Afterwards I bought her a very nice Winchester, lever action 410 shotgun, saddle gun, Of course will shoot ammo from buck shot to slugs to squirrel shot,,may I say she looks really good on the horse with that bad boy, almost no kick, hold it tight to shoulder.....yea baby...and its easy to handle and sure to back off any one..even at some distance..
I have several others but really like my cane sword..hehehehehehehehe
Just go for the full size barrett 50 cal and get it over with.