I've got one that I mounted on a Taurus G3, T. O.R.O.. The only "problem" was the screws Ruger supplied were a bit short, but Taurus had provided a selection of screws and plates in the TORO package.
It doesn't work in the dark, or even in really low light. Like in my bedroom at night. There is always a light on in the next room, so I have no trouble seeing. My computer monitor gives off light too, but the dot just isn't there. I think it's as much a question of where the light comes from, as how much. If the light is overhead, the fiber optic coil can pick it up. If the light is down low, or in front of or behind, the coil can't see it. In normal day light, no problem and although the dot isn't BRIGHT, I have no trouble seeing it.
It does seem to be zeroed for my G3. At least I can hit no worse than I do with iron sights. While I have fired it with live ammo, I shoot it mostly using a laser cartridge, and it's dead on with that.
Now, I got to the range yesterday and found, surprise, surprise, surprise, I can't see the dot, which is sort of an orange color, against an orange, yellow, or red target. Duhhhhhhhhh...the dot just blends right in with the target. It had worked fine against a black B-27 a week or so before, but I had left them in my other car so I figured I'd "make do" with what I had. At least the iron sights co-witness just fine.
Is it a GREAT alternative to a conventional dot sight? Probably not. I got it mostly because I was too cheap to buy a more expensive dot to put on a really inexpensive gun like the G3, but I wanted to try one. I got it from Bud's shipped, taxed, etc for less than the MSRP. It works fine for what I wanted. Sort of "training wheels" for a dot. I may or may not upgrade it at some point but for now it's doing what I ask it too. For a range gun, it's probably OK, but not so much for a self-defense gun.
