Please could you tell me what is meant by: to zero a rifle. At what range/s? How to go about.
I'm no expert on this, so maybe there'll be a more formal definition coming through. However, from my understanding... :naughty
Because the low power of air rifles, the trajectory is very bowed (a bit of a rainbow). The barrel points slightly up, which means initially the pellet will head skywards. Then old Gallileo's principles hit in, and the pellet comes down again.
Hence you can only adjust your scope crosshairs to intersect with the pellet's trajectory at a specific distance. If you choose your zero to be at the top point of the trajectory, then only at that distance will the pellet hit crosshairs. If you choose a different distance to zero it, then the pellet will intersect with the crosshairs twice (once on the way up, and once on the way down). e.g. my scope is adjusted to be spot on at about 20 yards, and 30 yards. (Hmmm, I suppose technically you could choose a distance so far away that the pellet drops below the barrel point, and then it would be only one point again, but that's a bit silly)
Say you decide to zero your scope for 30 yards, you'll put a target up at 30 yards, and adjust your scope until the hole appears where the crosshairs are. Now your rifle and scope are zeroed for that range...
Clear as mud eh?