zeroing your rifle will vary with reference to your ammunition, a 243 is a more than able round for the uk and depending on the beast your deciding to hunt your zero should vary, the change in grains and heads will alter your trojectory each time, so i think the best advice would be to find your most populer round that you will be using, say 100grain ball tip and grain solid slug, whatever it may be, and zero the rifle on your first round at 100yds, youl find by putting your second choice of round through will differ on your target, this is due to the flight pattern of the slug changing its c