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Riddle me this: Ballistic calculation
- Thread starter Unlicensed Dremel
- Start date
Use an internal laser bore sight, one that fits in the chamber of the rifle and spot it at the target. Then take the amount of bullet drop for the weight bullet you will be using for 200 yards and raise the spotting laser for the number of inches that the bullet will drop for that distance. Then bring your cross hairs down or up to the center of your target, you should be within a 1/2 inch of where the bullet will hit.
Things you will have to adjust for when using real bullets is wind, muzzle whip, powder charge, ballistic coefficient of the bullet.
But you should be fairly close.
Jim
If you can't afford a bore laser, you could do it the old fashion way by looking down the barrel of the rifle, but you will be much less accurate as to the center bore axes by that method and at 200 yards you could be way off. If using this method you should start at 25 yards and then zero your scope, then 50 yards and zero, then 100 yards and zero and finally 200 yards and zero your scope.
Things you will have to adjust for when using real bullets is wind, muzzle whip, powder charge, ballistic coefficient of the bullet.
But you should be fairly close.
Jim
If you can't afford a bore laser, you could do it the old fashion way by looking down the barrel of the rifle, but you will be much less accurate as to the center bore axes by that method and at 200 yards you could be way off. If using this method you should start at 25 yards and then zero your scope, then 50 yards and zero, then 100 yards and zero and finally 200 yards and zero your scope.
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Jim243, I've tried your suggestion with chamber bore sighters as well as anything else that'll optically align bore axis with scope axis so they're parallel at any range, then adjujst the sight vertically down range to the amount of bullet drop plus sight height above the bore axis point. Cartridges used were .222 Rem, .243 Win, .264 Win Mag, .270 Win, 7x57 Mauser, .308 Win, .30-06, .300 Win Mag and .30-.338 Win Mag.
No more than a 1/4 MOA error at 200 yards, you say? None of mine were closer than 1 MOA at both 100 and 200 yards. The heavy kickers had a greater error; the 30 caliber magnums were a bit over 2 MOA.
Your method assumes the rifle will not move from its aiming axis until after the bullet's left the barrel. That never happens; not even with a 13-pound 22 rimfire match rifle.
Best proof of this I know of is shooting a team match with all members shooting the same 30 caliber rifle and ammo. There's easily a 1 to 2 MOA difference in sight settings for a given range zero. That's because we all hold a rifle at different angles to our bodies and present different amounts of mass behind it.
Or, with a rifle that's very accurate and sighted in perfectly for you, put that collimator in it then see where the barrel axis points relative to were your sight's pointed.
Note that a zero one gets shooting their rifle resting atop something on a bench will be different than shooting an unsupported field position; prone, sitting, keeling or standing.
No more than a 1/4 MOA error at 200 yards, you say? None of mine were closer than 1 MOA at both 100 and 200 yards. The heavy kickers had a greater error; the 30 caliber magnums were a bit over 2 MOA.
Your method assumes the rifle will not move from its aiming axis until after the bullet's left the barrel. That never happens; not even with a 13-pound 22 rimfire match rifle.
Best proof of this I know of is shooting a team match with all members shooting the same 30 caliber rifle and ammo. There's easily a 1 to 2 MOA difference in sight settings for a given range zero. That's because we all hold a rifle at different angles to our bodies and present different amounts of mass behind it.
Or, with a rifle that's very accurate and sighted in perfectly for you, put that collimator in it then see where the barrel axis points relative to were your sight's pointed.
Note that a zero one gets shooting their rifle resting atop something on a bench will be different than shooting an unsupported field position; prone, sitting, keeling or standing.
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Unlicensed Dremel
Moderator
Thanks all.
Handyman79
Inactive
I just got one more thing to add. For a 200yd zero with an AR your sights should be set to shoot to point of aim at 50yds. So If your friend picked an object at 50yds and zeroed his sight to the laser dot (which would be much easier than a 200yd target) he should be about spot on at 200.