The most important aspect in regards to rifle accuracy is the bedding.
The bedding is the fitting between the stock and the barrel/action
assembly. This must be a consistent contact between these parts,
otherwise not much accuracy can be expected. The bedding should ideally
be a even spread out contact, with no pressure points. Since the action
usually has not such a tight fit from the factory, bedding epoxies are
available to ensure the best bedding possible.
The different contours and length of rifle barrels available can
impair or contribute to a rifle shooting accurately. Usually the
heavier the barrel the more accurate it will shoot. This is because the
barrel undergoes a harmonic vibration with each shot. The heavier the
barrel the more rigid it will be and it will be less subject to this
vibration. Also the length can effect the impact from this vibration.
If there is severe harmonic vibration frequencies the longer a barrel
it may become more inaccurate. The ideal barrel is usually the most
accurate barrel available at the desired weight, which depends on use.
Free-floating barrels provide the best accuracy in most cases. That is
if the stock is properly bedded, a barrel that has no contact except
the first couple inches, will be the most accurate. The contact between
the stock and barrel will create a inconsistency with point of impact.
By free-floating the barrel there more consistency with each shot
fired. Usually a U.S. dollar bill can be used to properly gauge the air
space between the stock and barrel of a rifle.