Roy, that´s right, but the effect of the reticle staying calibrated is twofold.
On one side, the reticle size- target size ratio stays the same. This means that a reticle that covers x inches at 100 yds, will cover 10 x at 1000 yds.
European reticles such as the 4, ret., and others, have a thick post on the outside and the inner part of the crosshair is thinner to allow better aiming. The distance or part of the target that the thin post or part of the crosshair covers remains the same no matter if you are in the low or in the high magnification of the scope. These reticles are rarely used to calculate holdover and sometimes can be useful at calculating distances, since the thinner part of the crosshair covers, i.e. (usually) 70 cm. at 100 m. So if you know that an animal is 70 cm. long, and fits exactly in the thin part, it is 100 m. away..
Now secod thing is if you wanna take a long shot, the crosshair may be a little too thick depending on the target size and the distance... that is happening to me with my swaro. if I attempt to shoot at long distances ( well, at least what I call long ), the crosshair is too thick . So if one is interested in LRS, and plans to use a first focal plane reticle, you must bear in mind the thickness of the crosshair. That´s why i am going with a S $B now with a mil dot - gen 2 type reticle... the mil´s are always mil´s no matter the magnification, and can be used for measuring or estimating any time, not just at max. power... and the reticle is still thin enough to attemp long shots at higher magnification.
