Many times I read the story the story about how 244 flopped and then was reintroduced as 6mm, about how this gave the 243 a leg up.
I was born after that came about. My story with 6mm starts with my dad. A new 6mm was purchased shortly after his favorite Rem 223 had been stolen. He was an active coyote and deer hunter and whatever else popped up. Fun yes but in the 70's times were tougher. Coyotes were worth 80-95 dollars skinned fleshed stretched washed and sewed. Deer meat was cheap and available. The rifle then was mainly a Ruger 6mm M77V with a Weaver K6 Wide angle. The recipe involved 85 or 87 gr. bullets from Nosler or Hornady, and H380. He would go to 100 yards downrange and make two crosses with black electrical tape on a box, one just about two inches above the other. The sighting in was done when three shots were all inside the intersection of the top cross when aiming at the lower. One year the rifle was off and there was consternation. Instead of adjusting the scope, dad put the rifle down, and went to the eye doctor for new glasses. When they came in, the rifle was right back on target.
I was indoctrinated early on the 6mm vs. 243 debate. I was told about things such as sharp case shoulders vs. graceful ones, and how extra case capacity is a good thing. He said that he could load it up closer to a 25-06 than a 243.
We were not landowners. But some of my dad's friends were. And individually at different time they have related to me some great shots he had made on a distant trotting critter. The hilltop shot from behind on the far running yote which toppled him over (and only one natural hole could be found). When a rancher tells you your dad is a good shot, it means something. This man and rifle fed us and put packages under the tree for several years.
There was the time a buddy wanted my dad to take him out after the big buck. The large man brought a big gun, and dad his 6mm. It was a crisp cold morning, with a dusting of snow across the meadow, when just coming into some golden tall grass at the edge of the willows a large mature whitetail buck erupted. He was in full acceleration and before long he would be hitting full stride and gone. The large fellow with us shouldered the rifle as my father began to take aim. In rapid succession both let loose. I had seen enough bang -flop on coyotes to know the rhythm, and timing, and to know who's shot dropped that buck in its tracks. Tha mount is proudly displayed on our buddy's wall. But two out of three knew who really dropped that deer.
That old rifle sat in the corner for about 11 years when times got better and fur went south. But getting into rifles myself now as a young man I had brought home a new thing, and just the ticket to beat my old man: a new Ruger target 25-06. I was getting it rested on the bench in front of a 200 yd target when out he came with the dusty old 6mm. " Let me show you what that 25-06 can't do." he proclaimed. He carefully rested that old rifle and loaded in three very old handloads. After the shooting I went to look. There were three 24 cal holes 1.25" apart at 200 yds. He always said that he seated bullets to the lands or very close, but when I measured the throat later that day, it was nearly shot out. Bullets almost left the case before contacting anything. I dont think he was aware of this, but faith in your equipment is a powerful thing.