Trigger, I have to ask.
Are you under the impression that other calibers are less touchy? When it comes to the type of precision and accuracy that it takes to be at the top of any Benchrest Discipline, they are ALL finiky.
I shoot both a 6mm and a 30, (and a 25BR in the past), and have done well with both, in group and score. In my opinion, keeping either shooting at a sub.200 level is equally difficult.
Now, keep in mind, I said SUB .200 level.
In short, I don't think a 6mm, (I assume you mean a 6PPC), is any more difficult to keep shooting at a championship level than a 22, a 25, a 6.5, a 30, etc.
Here is something to ponder. Many shooters get lulled into thinking that certain calibers, say a 30, are easy to tune because they can do the job in a certain venue. A shooter hits a 250 20x and, let's say he wins a match. When you examine his targets, you notice two of the 10's just barelly kissed the 10 ring. Now, that 10 is just as much of a ten as one that would have almost kissed the X. But, if you measure that shot from the center of the other four shots on the target, what the group would have been was a big ole "four".
Reality sets in when the shooter finally gets in a group match, and nails a .320 agg, and wonders what the heck is going on.
I saw this on quite a few targets that were shot at our Club Match this past week end. For that matter, I see it all the time. Even the winner, Vic Smith, (he won't mind me saying this), admitts that his Rifle was not up to standard, he did a great job with the conditions, which were pretty tough, and avoided the "9" that killed a couple other shooters chances. But he will admitt to anyone that he had at least 2, maybe more, shots that would have destroyed an agg in a Group Match.
I believe that there are several chamberings that have the inherant accuracy to compete at that recognized "sub.200" level. The 222, the 22 6PPC short, the 6PPC, the 6 BR .100 short, the 30 BR, and a few more. None has a magical grip on that illusive ability to stay in tune through the entire week end with no changes. That is, if your standard is that ".sub .200 agging capability".
I suggest you read some of the excellent writings by Jack Neary. While he primarilly is concerned with keeping a 6PPC and 133 shooting over the entire aggregate, what he says holds true for any extreme accuracy chambering......jackie