A 30 fps burst may shift the hit at 1,000 yards by approximately 8.5 inches. That is the sort of mute arithmetic that would make a dainty 100-yard body a miss when the ball is finally fired.
Long-range shooters discuss “accurate” rifles, but the rifles that continue to gain confidence in ugly wind and moving light tend to have something more mundane about them: they shoot the same today as they did the first day of zero. The selection of cartridge is important since certain rounds are more convenient to carry in that tight track- drop which can be counted upon, recoil that can be handled, and a bullet form that maintains its trajectory when the wind takes the initiative. This is why there are such old standards as .308 Winchester, 6.5 Creedmoor that continue to appear next to new working horses such as 6mm ARC and 6.5 PRC.
Neither is consistency a one-dimensional quality. It is a heap of little characteristics falling in place stable muzzle velocity, a lot of bullets remaining highly stable in the air, powder that does not walk as temperatures change, and a shooter who develops honest DOPE rather than rents it. All that clicking, combined, awards the basics of cartridge rifles ranging in different models over a broad scope of lengths. The same is true of the 6.5 Creedmoor using modern, high-BC bullets that ensure that wind calls are less painful, and there is enough recoil control that one can see the impact and correct without leaving the gun.
Temperature is the latent agent that continues to creep in the question of why did that one go high. Due to the heating and cooling of ammunition, powder burn rate varies and some propellants oscillate sufficiently to shift point of impact at range. A competitor of long range made it simple: temperature sensitivity is what we all must know about since at long distance you will miss your target just simply because of the temperature sensitivity of the propellant. That statement of Seth Swerczek, the Hornady Marketing Communications Manager, coincides with the results of the prudent testing: storing ammo in the sun or transiting between a cold morning and a warm afternoon can completely change muzzle velocity to the point of making a difference.
This is velocity variation where predictable cartridges differentiate themselves and lucky ones. The lesson to many shots that were observed on a big 6.5 Creedmoor test was simple enough: shooters have a way of learning experience through either pursuing speed or seeking consistency. The figures put it in terms of inches where a 50 fps change in muzzle velocity can wind the vertical hits in almost 14 inches at 1,000 yards. This is larger than the correction window of most practical targets, and it is compounded when a shooter adds little mistakes in range, position or wind.
Platform matters, too. The .223/5.56 family remains useful in long-range training due to low recoil it is easier to notice when a shot has gone astray and to learn wind, but only remains predictable when the bullets have been properly stabilized. The current AR-15 shooter is more inclined to the heavier and longer bullets and the stability has reduced to the twist rate. The rule of thumb with veteran builders is quite straightforward: go with a faster twist to prevent the dead-end of bullets that cannot lay down in flight particularly when shortening of the barrels reduces the velocity.
The same reasoning can be used to explain the popularity of 6mm ARC. It lengthens the AR-15, but not to the point of making it larger, and it is designed to use long, aerodynamic 6mm bullets with a normal magazine capacity. The normal factory performance of an 18-inch barrel will be 103-grain bullet at approximately 2,800-2,900 fps, the cartridge usually remaining supersonic to approximately 1,300 or more yards. At the field that translates to reduced drama in the wind and a more consistent path than a 5.56 where the targets are tiny and the distances are adding up.
On the other extreme is match-grade .22 LR, that imparts the same lesson of wind reading, follow-through, data logging, at rim fire ranges where errors can be noticed quickly. The rimfire crowd have been longtime followers of consistency by existing within a small velocity range. 1,066 to 1,100 fps is usually the most accurate range since it is always under the transonic transition, and the packaging and lot to lot consistency are also taken into serious consideration since they reflect on paper.
The foreseeable cartridges continue to gain a reputation since they minimized the number of variables that a shooter needs to battle. The rifle must still follow the true, the ammunition must still perform shot to shot, and the DOPE must still be tested in conditions of reality–but with a cartridge which is relatively easier to detect, long-range shooting is as near to a shortcut as it has.
