13 Spider Bloody Chain said:
AFAIK, bolt-action rifles are superior in terms of sheer accuracy.
Sorta.
First, some terms. In statistics, you have accuracy and precision. Accuracy is how close something comes to being "true," or to use the analogy of a bullseye, how close the shot comes to center. Precision is how repeatable the results are. Back to the bullseye, a precise grouping would be clustered close together. 100% precision would be all the rounds going through the same hole. High accuracy can be low precision, the rounds all hit the bullseye in different spots. A high precision grouping may be way off the bullseye. When speaking of inherent accuracy, we really mean precision. You can adjust the aim to get closer to the bullseye, tightening precision is not as easy.
Improving precision means eleminating variation. This variation comes from the rifle's action torquing while firing, the barrel flexing, the weight of the bullets, the number of powder grains, the position of the cartridge in the chamber, and how precisely the barrel is machined. Just to name a few. The action torquing is usually solved by bedding the action, creationg a stable and consistent contact area between actionn and stock. The reason for heavy barrels on is simple: a heavier barrel is harder to flex than a light one. This also means that, contrary to most expectations, a shorter barrel will probably be more precise than a longer one. A short barrel can be stiffer, pound for pound, than a longer one. (One common trick with Mini-14 rifles is to shorten the barrel a bit and recrown it. People say it makes their groups smaller) One reason why people tend to think of long barrels as being more precise is because they usually have a greater sight radius. The farther the distance between the front and rear sight, the easier it is to aim. Within reason, of course. If you can't see the front sight, it's a little too far out.
So, to bolt actions versus autoloaders. The top tier of high accuracy shooting is devoid of semi-autos. There's just more variation in an autoloading action. The lockup will never be as repeatable as the twisting lugs of a bolt action. The military, however, isn't in the business of punching holes in paper. Our enemies tend to move around and combat doesn't really give you those nice, prepared positions to calmly make your shots. Once that pucker factor is introduced, the accuracy difference isn't large enough to notice. One bad thing about a semi-auto for real sniping, I don't mean squad support, is the ejection of the brass. It's rather eye catching.