Alan Fraser is the webmaster at ozfclass.com , as well as being a member of the 2013 Australian F Open Team that brought home the Team Gold Medal from the 2013 F Class World Championships at Raton, NM in the USA. He is a 7mm/284 Shehane shooter himself.
He has done a statistical analysis of the Queens results (virtually a State Championship) for F Class Open and it is a statistical fact that the scores and average percentages (of the winners score) drops off dramatically after 700 yards.
Basically it is statistically proven that there are now a large number of F Open shooters with great scores out to 700 yards.......but that's where the wheels fall off for a huge percentage of competitors (me included) and from 800 to 1000 yards the results nosedive.
We are extremely fortunate to have had a poster called "Williada" take a strong interest in our sport and the ozfclass forum, over the past 18 months or so. Seddo knows who he is and what his knowledge levels are, and I am sure he will agree with me that Williada is a rare gem.
Anyway.....if i understand him correctly, Williada maintains that it's because a rifle can be tuned without POSITIVE COMPENSATION , to perform accurately out to 700 yards. Any rifle basically can and will have multiple tight, nodal tunes that will work out to 700 yards if the conditions are right (ie temp, humidity, elevation altitude, air pressure etc)
But from 800 yards to 1000 yards, understanding and including Positive Compensation is an important factor in develong an accurate load for "the longs". So effectively, most rifles need two loads to be developed...one for 300-700 yds and a second for 800-1000 yards.
The statistics that Alan Fraser has done seem to prove that far too many of us haven't done the extra work required to develop a "tuned" load specifically for the longs. The vast majority of Open Prize Meetings in my part of the world (SE Qld) are shot from 300-600 yards, and so we get a load that can win out to 6-700, and cease the load development. At my own local club range, we only shoot 300-700, and our annual OPM is 1 x 300 and 2 x 500.
I am shooting a new Bartlein barrel in 284 Win that is very, very accurate. I shot 90-7 out of 90 with it last weekend, at a Prize Meeting, to win the day 1 Sweepstakes and finished equal 4th on the main day, to win the Grand Aggregate for the overall event. Williada has helped me understand that I must develop a further load for longer ranges, because my barrel displays extremely neutral compensation . It is damned good out to 700 yds, but is almost guaranteed to fail at ranges longer than that. I trust his knowledge completely, and won't even try that current load at 800 plus.
So it's back to the drawing board, shooting more round robin groups with a chronograph on and plotting every single shot, looking for good tight groups with the slower shots landing highest.
So part of the answer to Rinso's question could possibly be that as most of us are effectively shooting an "untuned" load with zero positive compensation included in its development at those longer ranges, (ie it may well be superbly accurate out to 700... But its wheels will fall off past that) then the sheer ballistic advantage of a 7mm 180 gr Berger will see it consistently outperform the vast majority of 6mm and 6.5mm projectiles when shooting from 800 yards out to 1000 yards.
The few times that a non 7mm gets up at those longer ranges is possibly (a) an absolutely hummer barrel ...or (b) a very carefully developed long range load, put together by someone who either understood, or maybe just got lucky, with Positive Compensation.....or (c) a shooter capable of releasing near perfect shots consistently....or (d) a bit of luck......or (e) all of the above !
When you look at the names in F Open who are consistently in the Top Ten at Queens level events, and note the high percentage who choose a 7mm, it just can't be random.It sure as hell isn't just luck !
Every Queens I have ever been either shooting in, or closely watching results, is won or lost on the last day, shooting 800-1000 yards. And the same names keep cropping up in the Top Ten at the finish , with most of them shooting a 7mm.
Tony