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Old February 6, 2013, 04:33 PM   #22
Bart B.
Senior Member
Join Date: February 15, 2009
Posts: 6,318
SnowTrekker asks
At the end of the day, what should I expect at 1000 yards in terms of acceptable group size?
That depends on three things; how well you shoot, how good your rifle is and how good your ammo is. How stable the wind is adds to that equasion. For most folks starting out with factory barrels, their groups at 1000 yards subtend 3 to 4 times the angle they did at 100 yards. 1 inch (1 MOA) at 100 yards becomes 40 inches (4 MOA) at 1000 yards.

If I can expect my rifle to shoot at .5 moa at 100 yards, does that mean my groups at 1000 yards should be no larger than a 5" spread or is that unrealistic? It kinda' seems unrealistic over that distance given all the other factors that will come into play (wind, etc).
No, they won't. Even with zero wind and zero muzzle velocity spread, the small variables in bullet shape and balance are enough to cause their drag values to have a 1 to 3 percent spread. Which means those with more drag will drop more and strike lower than the ones with less drag dropping less and striking higher.

Add the above to subtle winds that always exist, even in calm air, and ones 100 yard group size tends to open up 10 to 15 percent for each additional 100 yards range past the previous one. Benchrest rifles shooting 1/4 MOA (1/4 inch) at 100 yards will shoot 3/4 MOA (7.5 MOA) at 1000 yards.

Note the .308 Win. bullets tend to have about 4 inches of vertical shot strining for each 10 fps spread in muzzle velocity.
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