Have had a number of shooting sessions with my BSA Light with the 21b Sight mounted. It’s given me a chance to experiment with it in its different configurations. From what I can see they stopped making this sight after WW1. I have looked in the Gallery and only find this sight on pre-WW1 rifles? What strikes me is how small and intricate it is, very cool for the collector. The distinctive feature is the sliding cover which gives you the choice of 3 different size aperture openings.


I naturally started shooting with the middle opening thinking it was the “normal” size, then went to the small one. Very hard for me to use even on a bright day, but I was in the shade. After much experimenting I went to the largest opening and the difference was amazing for me the sight picture was clear and I was putting the pellets in a 1/2 inch circle at 20? feet. This is where it’s going to stay, maybe it’s my old eyes? Would be fascinating to know what size this hole is compared to the 21a single size. Below is a consistent picture of each setting largest to smallest.





The other interesting thing to me is the sight is slightly tilting up from the base. This makes it perfectly perpendicular with the barrel given the stock slopes down? Not sure if this is a adjustment that can be made or a sign of proper installation? There are a number of small screws that could affect this. Not messing with what’s right to find out.



Lastly you can’t see but the base it a high polish blued steel. Something you don’t see nowadays. My installation is oddly back toward the stock “beak” and hits at 6 o’clock all the way down. I remember Tom Gaylord a airgun expert in the US saying he always did the best with larger aperatures. I found this true but we are both older shooters. Lol