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Post by wessir on Apr 17, 2022 12:23:19 GMT -8
For the ballistics settings, ballistic coefficients, who can you estimate or guess if you don't have published specs?
Muzzle velocities change by barrel length so when a velocity is published on the box, what length barrel is assumed?
The most 'interesting' setting is the sight height. Everywhere you look specs are for 1.5"
I'm pretty sure sight height means center bore to center scope. Is that wrong?
For the X-Sight the center scope to the rail mount point is about 1.75" and then about another 1.25" to the center bore. Is the sight height for X-Sight 3" on the AR15 platform?
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Post by number40fan on Apr 17, 2022 20:51:23 GMT -8
Best to have a true muzzle reading of the ammo being used with your gun. Which will require a chronograph.
Center of bore to center of scope is the correct Sight Height measurement. If you measure 3", use that.
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Post by mickb70 on Apr 23, 2022 10:53:44 GMT -8
For scope height....
With a caliper measure barrel diameter just past scope, divide by 2 then measure end of scope outer diameter, divide by 2, measure height from top of barrel to under side of scope add all 3 dimensions will give you correct height.
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Post by b308 on Jun 4, 2022 14:52:53 GMT -8
For factory ammo BC the trick is to find which bullet is loaded into your factory ammo, its not always obvious and sometimes you need to look around the internet. They are usually commercially available bullets from major manufacturers (Sierra, Hornady etc), and the manufacturers always publish BCs for their bullets.
Failing that, the hard way is figuring out BC with a chronograph. You will need to take a speed measurement at two distances (the further apart the better) and then plug those figures into a ballistic calculator. It will figure out the BC from how much the bullet slows down between two points.
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