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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Need some ballistics help...
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<blockquote data-quote="Bart B" data-source="post: 1134765" data-attributes="member: 5302"><p>Having used several ballistic programs for a given bullet and muzzle velocity, all don't give the same results for the same environmental settings.</p><p></p><p>Boxing your scope shooting groups is not to precise. Instead, tape a ruler at right angles to your line of sight 50 or 100 yards away. Then clamp the rifle in a fixed position with the scope on that ruler. Zero the reticle on the ruler then move the reticule 10 major units; MOA, inches per hundred, mills or whatever. See where the reticle is on the ruler. Do the grade school math to calculate the error.</p><p></p><p>The muzzle velocity you get with that rifle and load is probably different than what the 'smith got. It's normal to see over 70 fps difference in average fps across several people shooting the same rifle and ammo. We all don't hold the rifle against our body with the same pressure; Newton's Law messes up the numbers across several people.</p><p></p><p>All scopes of a given make and model do not have exactly the same adjustment amount per click. All the lenses in each one don't have exactly the same focal length and that can cause a few percent spread in adjustment amount per click across all of them. It's caused by a small spread in target image size on the reticle plane for a given magnification set on the scope.</p></blockquote><p></p>
[QUOTE="Bart B, post: 1134765, member: 5302"] Having used several ballistic programs for a given bullet and muzzle velocity, all don't give the same results for the same environmental settings. Boxing your scope shooting groups is not to precise. Instead, tape a ruler at right angles to your line of sight 50 or 100 yards away. Then clamp the rifle in a fixed position with the scope on that ruler. Zero the reticle on the ruler then move the reticule 10 major units; MOA, inches per hundred, mills or whatever. See where the reticle is on the ruler. Do the grade school math to calculate the error. The muzzle velocity you get with that rifle and load is probably different than what the 'smith got. It's normal to see over 70 fps difference in average fps across several people shooting the same rifle and ammo. We all don't hold the rifle against our body with the same pressure; Newton's Law messes up the numbers across several people. All scopes of a given make and model do not have exactly the same adjustment amount per click. All the lenses in each one don't have exactly the same focal length and that can cause a few percent spread in adjustment amount per click across all of them. It's caused by a small spread in target image size on the reticle plane for a given magnification set on the scope. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Need some ballistics help...
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