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Rifles, Reloading, Optics, Equipment
Long Range Scopes and Other Optics
horrus ltd. scopes
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<blockquote data-quote="Warren Jensen" data-source="post: 13729" data-attributes="member: 21"><p>There is a major problem with all ballistic trajectory predictors,i.e. computers, programs, reticles, that assume a fixed trajectory and only compensating for atmospherics. When shooting to and through transonic in any cartridge the particular characteristics of the ammo in each rifle have to be accounted for.</p><p></p><p>We are delivering our first versions of the Advanced Ballistic Computer, by CheyTac Associates, to military customers in January. It is extremely sophisticated, accounting for the following factors, muzzle velocity in the particular rifle, twist, muzzle jump, temperature, true barometric pressure, ammo temperature, winds at three distances, slant angle, azimuth and latitude of fire for corealis effect, spin drift(precession), and lead for moving targets. We routinely get first round hits on mansized targets to transonic with nonbalanced projectiles and first round hits through transonic with balanced projectiles. For the .408 that means 2500 yds., but we have also used it in .308 Win., 300 Win. Mag., 338 Lapua, and 50 BMG with multiple military and civilian loads in each. At those distances you have to account for all errors and cannot discount anything. Fifty fps. difference in muzzle velocity from one gun to another or one lot of ammo to another means 30 inches of vertical and 5-10 inches of horizontal at 2000 yds. You have to know what your muzzle velocity is at the air tempurature, gun temperature, and ammo tempurature you are shooting. Fixed formulas are worthless as various powders, bullets, and barrel steels react differently. </p><p></p><p>It is not possible to account for all these variables in a fixed reticle. It is very difficult to account for all of these variables even with a sophisticated computer and real time atmospheric data collection. Most painfully difficult of all, the program has to be adjusted and customized for each shooter, with his gun and load if you expect first round hits to and past transonic and flight times past 2.5 seconds. (For practical terms this does not include the .308 Win. as it does not exceed 2.5 second flight times) For ranges to 1200 yds. fixed reticles can be very effective and fast for someone who is trained and practiced with that reticle and his rifle. </p><p></p><p>For the record, you do not have to be a world class shot to be on target past 2000 yds. A very good shot will do. You do have to have world class equipment and a very detailed understanding of the equipment and ballistics to be accurate out there. There are no shortcuts when first rounds hits are the criteria.</p></blockquote><p></p>
[QUOTE="Warren Jensen, post: 13729, member: 21"] There is a major problem with all ballistic trajectory predictors,i.e. computers, programs, reticles, that assume a fixed trajectory and only compensating for atmospherics. When shooting to and through transonic in any cartridge the particular characteristics of the ammo in each rifle have to be accounted for. We are delivering our first versions of the Advanced Ballistic Computer, by CheyTac Associates, to military customers in January. It is extremely sophisticated, accounting for the following factors, muzzle velocity in the particular rifle, twist, muzzle jump, temperature, true barometric pressure, ammo temperature, winds at three distances, slant angle, azimuth and latitude of fire for corealis effect, spin drift(precession), and lead for moving targets. We routinely get first round hits on mansized targets to transonic with nonbalanced projectiles and first round hits through transonic with balanced projectiles. For the .408 that means 2500 yds., but we have also used it in .308 Win., 300 Win. Mag., 338 Lapua, and 50 BMG with multiple military and civilian loads in each. At those distances you have to account for all errors and cannot discount anything. Fifty fps. difference in muzzle velocity from one gun to another or one lot of ammo to another means 30 inches of vertical and 5-10 inches of horizontal at 2000 yds. You have to know what your muzzle velocity is at the air tempurature, gun temperature, and ammo tempurature you are shooting. Fixed formulas are worthless as various powders, bullets, and barrel steels react differently. It is not possible to account for all these variables in a fixed reticle. It is very difficult to account for all of these variables even with a sophisticated computer and real time atmospheric data collection. Most painfully difficult of all, the program has to be adjusted and customized for each shooter, with his gun and load if you expect first round hits to and past transonic and flight times past 2.5 seconds. (For practical terms this does not include the .308 Win. as it does not exceed 2.5 second flight times) For ranges to 1200 yds. fixed reticles can be very effective and fast for someone who is trained and practiced with that reticle and his rifle. For the record, you do not have to be a world class shot to be on target past 2000 yds. A very good shot will do. You do have to have world class equipment and a very detailed understanding of the equipment and ballistics to be accurate out there. There are no shortcuts when first rounds hits are the criteria. [/QUOTE]
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