I bought the .22 Magnum NAA mini-revolver 30-35 years ago. Shot it enough to tell that it shot WAAAAAY low -- and that I could not hit much with it. I thought it might be because of the little grips. Then they introduced the grip/holster. I wanted one, but it was only for the .22LR version. Then they added both fat and long grips to the list, but they did not appeal to me. Since I could not shoot worth a darn with it, it got put back in the back of the gunsafe and I did not shoot it again for a long time.
I was recently watching the Hichkock45 on YouTube and he said they now make a grip/holster for the .22 Magnum, so I ordered one. It did not fit. I e-mailed NAA and they said that my gun was old enough they did not fit. However, they would send me a new mainspring and once installed, the grips would fit (the main pivot pin for the grip/holster went right through the mainspring).
NAA sent me a newer mainspring and I eventually installed it. The top of the spring has to fit in a notch in the hammer. When bending the bottom of the spring with needlenose pliers and pushing it upward, it is really easy for the top to slip out of location, over the notch. It is easy to tell when that happens; the hammer will not move. Eventually, I was able to get both ends of the mainspring into their proper places at the same time. The grip/holster fit perfectly. I don't feel much difference between the old spring and the new spring. I don't really know why they changed it.
I took it to the range to try it out. It still shoots WAAAAAY low at 5 yards. The small grip was not the reason for that. By lining up the bottom of the front sight with the top of the rear "sight", I was able to shoot in the general area of the center. It is never going to be a target gun, but it does shoot (or I shoot) better than it did before with the small grips.
I once used to carry the gun about 30 years ago when I was between real jobs for a few months. I was working as a guard on the midnight to 8AM shift at a manufacturing plant that had had a number of break-ins and thefts. I had to walk a 20 minute route once an hour while marking my presence at about 10 different places along the route. The company had strict rules that you could not carry ANY weapon (including a flashlight with more than 2 D-cell batteries or a one with a metal housing). Remember, this was before cell phones. We were expected to outrun the thiefs back to the guardshack and call the police from there. The company supervisor checked we were not sleeping, neglecting our rounds, or carrying a weapon at least once every two or three shifts. He never found the NAA revolver. I carried it in a hardcover eyeglass case in my shirt pocket. Luckily, I never had to use it.
Unfortunately, the grip/holster makes it too large for an eyeglass case, but it is really not that much bigger when folded, than it was before. I bet I could still find a place to hide it again, if I had to.