I have a Nikon Monarch 1200 and it works well out to 500 - 600 yards in most situations. My brother in law has a Bushnell 1500 and we were ranging different things and mine consistently read one or two yards farther than his but we were ranging things out to 900+ yards so I was amazed that they were that close.

Any laser rangefinder needs to have the laser reflected back to it to work so they are always going to work best on flat reflective surfaces that are perpendicular to you. For instance we were able to range moving semi-trucks at 900+ yards on the highway near his house, but neither of us could range a windmill fan that was 1/2 that distance.

I've had one instance where I couldn't range an antelope at right around 200 yards (I stepped it off after I shot the antelope) but it was because the antelope was laying down and I was laying down on a stalk and we were both on flat ground with some sage brush. I just couldn't get a return on the laser. If I had stood up I probably could have got the distance, but I wasn't about to do that and have them run off.

On most rangefinders the rating is for a large flat surface perpendicular to you so I've always heard that you should assume that it will work at 50% of it's rating in real life circumstances.