ELR and what it actually means
ELR stands for "Extreme Long Range". And what does it actually mean? When is it Extreme and when is it just a normal Long Range? I'll try to answer that.
Extreme means something extra. Generally shooters agree that this "extra" is a state where the bullet becomes unstable in its flight. This occurs in the so-called "Transonic Range" which is the transition from supersonic to subsonic speed. Due to physical laws this occurs between approximately 1.2 Mach and 0.8 Mach. The sound speed is usually about 340 m/s under normal conditions. Thus it is a speed range between 410 m/s and 270 m/s where the bullet tends to destabilize and lose accuracy.
But the distance where it occurs is of course dependent on the caliber we use. From left 338 LM AG, 7mm Practical and 6.5 Creedmoor.
So for example for .308 Win will be "extreme" already over 1000m which is for 338 Lapua Magnum just easy. And what if we will shoot .22 Long Rifle? There is already 200 meters a big problem...
However it is a fact that if we are considering shooting at "extreme distances" we probably mean the equipment for that purpose. And of course including caliber and ammo.
And from this general point of view the shooting is divided into several types... Although unofficially this division most shooters respect.
Mid Range (MR) means up to 300m. Since these considerations have their origins in America 300 yards are the range - which is about 275 meters. But the reality is that many shooting ranges in Europe are 300m - so these 300m can be considered an adequate threshold for this division...
Long Range (LR) means between 300m and 1400m. In America the distance is 1500 yards which is about 1,370 meters. For simplicity however we will consider a distance of 1400m...
The Extreme Long Range (ELR) is above 1400m. For some calibers it is still relatively short distance but it is necessary to realize that other things are playing a role at these distances. For example difficult observation of targets and hits, wind, bullet derivation, Coriolis effect, Earth rotation and others... These influences already play a significant role so even if we use caliber for which is theoretically 1400m "easy to reach" - in real life it is not so easy...
And so shooting over 1400 meters becomes really "extreme"...
