RE: Any info on Shepherd Scopes
well they like all bdc's are probably pretty close to 700 yds, its all simple math if you shoot a bullet in the range of what the bdc reticle is set for.
beyond 700 yds, there is no way they can be right on in all conditions, especialy in the east where we have huge swings in the bar pressure.
It goes like this guys bar pressure is a combination of air pressure and altitude, what it actualy does to your shooting is effectively changes the BC of the bullet, tempatures change the velocity (though not to the extent that BP changes BC)
ok just ran some numbers through my ballistic program
a 270 weatherby mag, firing a 150 nosler bt with a BC of .496 at 3130 fps, sighted dead on at 262 yds drops 245" at 1000 yds at sea level in standard atmospere,59 degrees, 29.62 bar pressure, 30% humidity
same cartridge at same velocity, same sight in, with a bar pressure of 32.5", 20 degree temp, and humidity of 80% drops 305" at 1000 yds, the conditions changed the BC to .388
so how do you doctor that 55" of drop into a sheapard to effectivly hit your target at 1K when the weather changes?
Like I said, the right way to shoot long range is to dial.
RR
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