The only measurements I left out of the description in my original post were two that are best illustrated in the third picture in that post. The height of the magazine adapter from the bottom to the very top of those two points is 1 3/4 inches. Disregarding those two points (measuring as if they were not there), the height of the adapter from bottom to top (again, disregarding the two points) is 1 11/16 inch (this is one of the two measurements left out of the original post). The width of the groove itself, measured from outside-to-outside, is 11/32 inch (this is the second of the two measurements left out). Hope this helps!Unless you are in the US military....It's still inches and feet where I work in Canada even though I was one of the first generations to learn metric in school.....The influence of the US's stubborn refusal to change is felt in North America.
Minimouse, any chance you can post the dimensions that are cropped out of the photo?
I have a similar adapter for my Kimber SVT 22LR. It fits into the mag and allows for only one shot. It' s made out of the white polymer from a cutting board. Can pick them up probably cheap either on sale, or in a thrift shop. It seems to make a perfect material for a single shot adapter.
When my NS522 gets here I may go that route for a single shot adapter.
Funny, I was thinking doing the same thing.
Actually, I've already bought a cutting board but I haven't started the project because I just found another cutting board that's black (no need to paint). So, I'll make an adapter when the second board arrives.



























