I recently purchased a 5 mW green laser with Picatinny mount, and I have a short Picatinny rail on the bottom of the forestock on my Hatsan AT-44 Long .25 cal PCP.... It occurred to me that with the laser mounted there, about 4" below the boreline, and the scope 1.5" above the boreline, they could be set up to intersect, and by comparing the position of the laser dot to the Mil-Dots, you end up with a rangefinder.... Here is a plot of what I am proposing, using ChairGun....



As per usual, the Line of Sight through the scope is the horizontal red line.... The trajectory is the curved green line, and the laser is the blue line.... I set ChairGun up using 12X with a 1/2 MilDot Reticle, and the light grey lines are the Dots and half-dots.... The Blue dots are where the laser intersects the reticle points, and the idea is to set the laser so that it aligns with 2 MilDots up at 100 yards.... This places the intersects with the other upper Mil-Dots (for this setup) at 78 yards for 1-1/2 up, 65 yards for 1 up, 55 yards for 1/2 up, and 47 yards for the crosshair.... If you are closer than 47 yards, the laser dot will be below the crosshair, which works fine, because with this setup I have a point blank range of 11-46 yards, so if the laser is below the crosshair, I would just hold dead on....

It the laser appears on the target above the crosshair, then I know I need holdover for the shot.... How much holdover is shown by the green dots directly below each blue dot on the graph.... If the laser is between MilDots, then the range would be as well.... My intention would be to make a chart showing the laser dot position, and the corresponding holdover, both in MilDots.... something like this....



Obviously, you can interpolate between those points as well, and it might be useful to do that for the second half of the chart where the gaps in the ranging are longer and the holdover more critical.... I haven't tried this idea yet, but I though I would share the concept with you as I haven't seen the idea before....

Bob