Still, I would never expect her to make the right choice at 4, but it is good to know at least some of what we teach her sticks.
I think that's a great attitude.
To those who would suggest that 4 year olds are able to reliably exercise competent judgment around a loaded firearm, I would offer the following observation:
I have, during the course of my career, interviewed thousands upon thousands of children regarding their recollection of events as they relate to an abuse scenario and/or a criminal investigation. Many, many of these children have been in the 4 year-old range. I have also heard a very great number of their parents describe for me exactly what these children know, don't know, can and can't do, will and won't do, etc.
My experience has been that, developmentally and cognitively, there is no such a thing as an average 4 year old any more than there is such a thing as an average gun-owner. There is an absolutely ENORMOUS difference between children and their development at that stage. There are children that, at 4 years of age, can write full sentences, provide detailed descriptions, verbally express their emotions, play musical instruments, etc. There is also no shortage of 4 year olds who cannot be interviewed because their speech is unintelligible, they don't know even basic body parts (eyes and nose, etc.), they won't stop sucking their thumb when a stranger enters the room, they tend to poop in their diaper when a stranger enters the room, etc.
And, predictably, many parents are absolutely shocked at what their children say and do when objectively interviewed. In fact, the PD I worked for (in a very gun-friendly community) conducted a gun-safety experiment, like the one described, in conjunction with local media. Utilizing a disabled service weapon, several "well-trained" children, well over 4 years of age (one of them the child of a high-ranking police official), were observed in a room with a camera and one way mirror. Upon finding the weapon, to the astonishment and high dismay of each of the parents (all gun-owners and very confident of their children), all but one picked the gun up and began to manipulate it. All of them realized a need to tell a parent, but not before playing with the gun. One of the children began pointing the gun in various directions and having a pretend shootout. Another took up a defensive position behind the door as if waiting to shoot an intruder.
While I think it is reasonable to teach children about gun-safety at an early age, it is, IMHO, absolute negligence and madness of the highest order to expect good judgment from a 4 year old to the extent of leaving a loaded gun accessible to them.
YMMV.