HKT was approached about a year ago to develop a round that was capable of being shot at a range of 3 miles to break the world record for longest shot from a small arms weapon. The result was the .50 RS. This is a very unconventional cartridge. Based off of armor piercing tank rounds, it is a .50 caliber fin stabilized discarding sabot round.
It works by focusing all the force of a .50 BMG powder load into a 70 grain tungsten projectile. After the round clears the barrel air pressure rips the sabots away from the round leaving just the penetrator. In order to be within a scopes range of adjustment it must move at a consistent speed of 4000FPS or better.
Almost everything for this project is done. All that remains is to manufacture the round and a rifle capable of shooting it.
If you believe in this project, then please support it in whatever way you can either by donating or by spreading the word about this project or any of the other avenues of research here