Out to say 25 meters they're ok, but were intended for target / match shooting. Any further away and accuracy will suffer. Great on rats at shorter ranges, hit like a brick, thanks to the flat head.
On the other side, if your rifle likes them give them a try and see from what range they start to lose their accuracy, if that's beyond 40 meters, no problem , stick with them. Otherwise find yourself a nice dome head pellet from one of the proper brands : AA, JSB , H&N