First make sure the gun is unloaded!!!!!!! Check it twice. Then proceed as directed below.
Have the woman or kid hold their arm down at their side. Bend the arm at the elbow 90 deg, with the hand, and trigger finger, extended in line with the forearm. Place the gun stock in the crook of the arm, against the bi-cep. Have the gun running along the forearm. Extend the trigger finger and reach for the trigger. If the trigger finger does not reach comfortably on the trigger to make a correct trigger pull, the stock is too long. If trigger finger goes beyond the trigger, the stock is too short. If the trigger finger comfortably fits the right spot on the trigger the stock fits.
For a stock that is too short, simply changing or installing a recoil pad, or a few spacers, will often do the trick. If it's too long, the best thing is to take it and the person doing the shooting to a gunsmith. With some guns you can purchase a Youth Stock, That is often all that is needed for a woman or teen.
Yes, I know this is very basic, but you will be surprised at how many men (Fathers, and Grandpas) I run into teaching shooting classes for kids, that don't know this. They want the 10 yr old kid to shoot their own gun, then they bring in a full length stock on a .22rf. Often times I will mark it where it needs to be cut to fit the kid, and you can see their eyes almost pop out of their heads. I then tell them, "This is an adult size gun, just hang on to it till the kid grows up".
My Go-To-Gun is a Handi 30-06. I have a shortened stock on it. My standard length of pull is 14 1/2". This gun is cut down to 13" even. People often ask why it is so short. I wear heavy Goose Down coats or vest when out carrying this gun in the Alaska winter. The shorter stock makes it easier to shoulder the gun, and accounts for the extra thickness of my outer wear.
The Handi makes a good gun for a woman or child. Short barrels, and no long action make for a compact gun balanced well for a small person. Men, Husbands, Dads, and Grandpas, the worst thing you can do for a wife, son, daughter, or grandchild, is have them shoot your gun. The stock that fits you properly and has little recoil for you due to proper fit, will knock the snot out of them. They will now be so gun shy it will take some serious work to get them over it. That is why most wives refuse to go hunting, or shooting with their husbands.
Now take my wife, she is 4'11", and when I started working with her she weighted 95lbs, she was afraid of guns. Her Dad had done her a bad turn having her shoot his hunting rifle, as a teen. I bought a Remington .44 mag lever action carbine. Had the stock cut down to fit her with a good quality recoil pad installed (11" pull). Work with .44 Special loads and after one summer she was ready to graduate to full mag loads. I then got her a Mossburg 12ga pump. Had this gun cut down to fit her. Took her to the Skeet Range to practice, using Skeet loads. Next thing I knew she really got into Skeet Shooting and had bought herself a 20ga over and under skeet gun.
At this point she took off on her own. She took several shooting classes. Then she obtained an NRA shooting instructor certification, for Rifle, Pistol, and Shotgun. She went and bought herself a Remington 7400 Auto in 30-06. Wanted something big enough to kill a Grizzly. She took that new Remington to a just starting out gunsmith to have it cut down to fit. She told me the gunsmith almost cried saying, "Nobody else will ever be able to shoot this gun". She replied, "They better not, it's my gun". She said that shut him up. Since then when ever the mood strikes she buys a gun. What ever strikes her fancy. (Most women just buys clothes and shoes, she buys clothes, shoes, and guns). I honestly don't know how many pistols she owns, but .357 is her favorite caliber. She has her own vault, and she says the contents is none of my business. When our son was 5, she taught him to shoot using a little Chipmunk. At 8 she commendeered my Contender, put a youth stock on it, and a match grade 22rf carbine barrel for the boy. At 10 she bought him an Anchutz, I got my Contender back. When he turned 12, and reached her height, she started having him shoot her guns. He has turned into quite a shooter himself. They both love skeet, I can not keep shot shells in the garage. They shoot them up faster than I can reload them. According to her since I don't work, my job is reloading shot shells.
OK, OK, I got a little carried away. Started out something simple, then I got off on a tangent. Oh Well, that's me. Rog