Define long distance?

For the most accurate chairgun setup...

Weigh some pellets, collect a batch of the same weight to use for your crono testing.

Chrono your gun at the muzzle and again at a set distance with your weighed pellets.

These 2 will be able to create an accurate BC for your pellet and the correct muzzle velocity for your gun.

Then an accurate zero is needed, like spot on, gun clamp, bench and indoor range till you can pellet on pellet at your zero distance.

Then you need the correct scope to barrel measurement, most people do this wrong by just measuring between the centreline of the barrel and the centreline of the scope, that IS NOT how it should be done, it should be measured at the end of the barrel and be the distance between where the crosshairs project on an item at the end of the barrel and the centre of the barrel (note: 'barrel' not moderator), full instructions are in the manual...

Then you measure and input the distance between the end of the barrel and the reticle (centre turret) and input that, then you have chairgun set up as close as possible...

Then the wind blows, the temperature changes, your pellet weight isn't spot on or your rifle is having a bad day and it all goes to shit anyway lol