Federal 250rd Low Recoil, LE ammo 9pellets. I am barely 5ft tall, dont weigh much, and I shoot them just fine. Its repetition and practice. A bit more gym time, strengthen up should help too. Blew off 25rd's then switched to cheaper fio rounds, after getting stronger went from using 9mm only to also 40. From avoiding my shotguns, to shooting them normally. Went from 90lbs to 112, muscle and leaning. Went from soft skin, to tight skinned and firm
your wife just needs practice, and to grow a tolerance to the kick via training, as well gyming. Its what I suggest to EVERYONE I know, and after 60-90 hard gyming days, they aren't bothered by recoil/kick anymore. Just suggestion.