greybeard
Herd Master
It's probably directly proportional to the amt of $ spent on the laser and mounting hardware.How far out does the laser and bullet accuracy start to vary?...and do they make them for revolvers?
The dot itself, being a very focused type of 'photon' doesn't drop or bend. It travels in a straight line at the speed of light. (who woulda guessed?) Theoretically, the range of the laser is unlimited, But over distance the little dot will grow in size with non-military class1 & class2 lasers. What begins as a pinpoint at the firearm, at 200 yards, may be as big as 4" in diameter. With a good setup, the bullet should still fall within that 4" diameter at 200 yard range impact--depending on the initial range you sighted in at. Remember, some morons have taken a cheap classroom laser pointer, and pointed them at aircraft several thousand ft in altitude, and caused pilots to file reports with the FAA/homeland security.
The quick answer to your question is generally 'farther than you can easily see".
For most revolvers, the easiest might be a barrel mount. There are all kinds of them. I use a barrel clamp on type on both my sks and my .22.
There are dozens of different mount clamps for revolvers. Some mount on the barrel, some mount on the frame just above the cylinder, some come as a specific kit where you change the grip and the laser is integral to the grip. The same for lights.