...when the aiming error and holding error induced by humans are added back in, both of which are greater than the inherent accuracy to be found in a good gas gun, it is very difficult to establish which action is more accurate.
In looking at the NRA High Power Match results, bolt guns tend to shoot better scores than gas guns. Bolt guns have faster lock times, simpler designs and lighter-crisper triggers which makes them easier to shoot more accurate than a gas gun with equal accuracy when both are fired from accuracy cradles. Bolt guns also allow better handloads made for them for reliable functioning and accuracy. I doubt gas guns will shoot as accurate as bolt guns when fired from accuracy cradles with ammo they're reliable with.
By the way, notice that the NRA target is only 2 MOA. Basically if you can shoot 2 MOA for 80 rounds all the way out to 600 yards, you would shoot a perfect score. For the four day NRA XTC Highpower Match at Camp Perry, I don't think anyone has ever shot a perfect score. All of the top competitors have rifles capable of half MOA, so, given that these rifles shoot into one quarter of the bull, there ought to be lots of perfect scores, but there are not. You would think that so many internet posters claiming they always shoot sub MOA, at all conditions, at least one of these keyboard shooters would set a National Record.
A number of shooters have won the National Matches with target rifles built on the AR15 action. Carl Bernosky is one.
http://www.6mmbr.com/6brblog.html
COMPETITION--Bernosky Sets New High Power Record: 2007 Camp Perry National High Power Champion Carl Bernosky added another milestone to his list of achievements this past weekend. Shooting the same AR15-platform rifle that carried him to victory at Camp Perry, Carl shot an 800-41X score on the New Holland (PA) 200, 300, 600-yard National Match course. When certified, that will be a new National record. The previous record was an 800-38X (shot by T. Lawton in 2005). Carl modestly downplayed his achievement: "This time the close ones were on the inside instead of the outside."
In High Power matches, competitors shoot in three different positions -- standing, sitting, and prone -- and iron sights are used. This makes High Power one of the most challenging of all rifle disciplines. Carl feels that his AR-platform gun does give him some benefits over other rifle designs. Carl noted: "For me, I shoot better standing scores with the AR. I can't tell you why exactly, but certainly the self-loading feature of the rifle allows me to maintain position better shot to shot. The other advantage is in rapid-fire prone. There I think it is a real plus not to have to work the bolt."
Carl Bernosky's rifle features a custom upper built by John Holliger on a Smith & Wesson M&P15 lower with Geiselle trigger. The upper has a 26" Krieger barrel chambered in the 6mm Hagar. This is a new wildcat cartridge based on the 30 Remington case, necked down to 6mm. The 6mm Hagar resembles a 6.8 SPC with a .100? longer body, 30-degree shoulder, and greater case capacity. It has a .420 rim diameter, and is formed from .30 Remington brass. At New Holland, Carl shot alongside Robert Whitley. Carl said he was impressed by Robert's new 6mmAR Turbo round. The 6mmAR Turbo is based on 6.5 Grendel cases necked to 6mm with the shoulder blown forward slightly. Carl told us: "If Robert's 6mmAR Turbo can really shoot the 105s at 2880+ fps, then it should be competitive with the 6mm Hagar, and the brass is available right now. Whitley's cartridge looks like it has great potential."
For ultimate mechanical accuracy, the bolt rifle is more accurate. But, in a game such as Across the Course, you have to shoot standing (200 yards), sitting rapid fire (200 yards), prone rapid fire (300 yards), and prone slow fire at 600 yards. The "best" rifle is a compromise. One year someone analyzed the scores of the top shooters, and what separated them was standing. A self evident truism is that you win the match standing and lose it prone. This is so true. Everyone at the top level cleans the rapids, they are only a point or two different at 600 yards, but standing, standing is a house of pain and torment.
Palma shooters, I don’t recall any Palma Shooters using gas guns. In their game, the bolt rifle is the best platform.
I would like all of those claiming that there is one best action, to go out and shoot one of these events. If you can’t hit an eight by eight foot target standing at 200 yards, it really does not matter what action you are using. And then, get you out to 600 yards. Recently I was talking to some bud's, one was paired with a guy who was supremely confident of his 600 yard zero, because he had a firm 50 foot zero. Needless to say, the poor pit pigs worked very hard that day, as Mr. 50 Foot was all over the place, sometimes, not even his target.