IMHO, 125 yard shots on deer sized game aren't a problem with a 4 MOA dot. Bullet trajectory starts to become an important issue past the 100 yard mark.

I shot this N. GA whitetail with my 454 SRH and the 4 MOA 30MM Ultradot.


When I shot the deer, I did not have a rangefinder and estimated it to be a little over 100. The bullet struck the bottom of the chest cavity, breaking his right front leg. I later returned to the spot with a laser rangefinder and it turned out to be 149 yards. This is the longest shot that I have ever made on game with a revolver and wouldn't want to try it again without a steady rest and a rangefinder.

Here's another 125 yard shot; this South African kudu was taken at 126 if I remember correctly with a 3.25 MOA Trijicon RMR on my FA 454:


The point being, 125 yard shots with red dots are doable with the right gun and load and a steady rest. HTH...