i don't know how long ago they started making them but i started shooting them the first time i found them.i started out with a 295g PB & 70g of pyro & killed deer,moved to 100g pyro & killed deer,that was with a cva ss Apollo ,i bought a new cva bolt hunter & killed several with the same load.moved the load up to 130g & most were bang flops, bought a new optima pro & have shot a bunch of deer with the 295g & 100g of pyro & 777.i have moved up to the 777 mag pellets & down sized the PB to a 245g,it will be next season before i get another shot at a deer with that load but i put 1 down with a head shot this year that was impressive .most deer have not gone but a few feet,had 1 run 70y after she turned hard as i squeezed the trigger.i have had 2 6pts run run this year with their hearts busted by a 300wm,1 went 70y the other 100y ,all deer are different & they have a great will to live,i don't do shoulder shots & wait for a chest cavity shot.i think a lot of lost deer were shot where a major bone absorbed most of the bullets energy or fragmented it & didn't make it into the chest cavity.most all of the lost deer were hit perfectly too from what i have read ,as long as they keep working as good as they have been for me i see no reason to change because somebody else lost a deer with a perfect shot with 1,i have had many bullets deflect & still kill deer,i also have had a few that plumb missed ,i have not lost a deer yet with 1 & hope i never do.i cant say the same thing about arrows though ,mike300wm