Bad scope

[Flatfishhunter]

I purchased a Leupold VX6HD 3-18 to use on a 6BRA hunting rifle. I can't get my ballistic software to match actual target point of impact. When I zero it at 100 yds, then shoot at 200 yds (without the elevation turret), my point of impact is 1/2" high. Other distances also show about 2 MOA difference between the Applied Balistics apps recommendation and my actual point of impact. I have meticulously checked my MV (2914 fps), scope height (1.84"), and distance to targets. For a recent hunt I had to take this scope off, and replace it with a Nightforce ATACR. It's point of impact jived with AB data.

I've found that some people teach that there is only one point of convergence between the scopes line of sight and the bullets path, and others say that there ate two points of convergence (one where the bullets path comes up through the line of sight, and another where it drops down through it. Which is correct?

Is this Leupold defective or is there some adjustment I'm missing?

 

[Mr.Knowit all]

What is your scope height to the bore center?

 

[JEFFPPC]

I thing your confusing real range results with computer generated information. I consider apps as a rough means of getting on target, nothing I want to compete with or hunt with.

 

[dstoenner]

2 points of line of boresight crossing. First is usually about 25-35 yards. The second crossing is somewhere between the first crossing and the target

 

[pdhntr]

2 points of line of boresight crossing. First is usually about 25-35 yards. The second crossing is somewhere between the first crossing and the target

The line of boresight is not crossed. The bullet, as it leaves the barrel starts dropping (due to gravity) and can't cross the line of boresight. The exact center of the bore will be slightly above the exact center or the intended point of impact on the target, the amount depending on the distance from the muzzle. This is why experienced boresighters will elevate the "boresight of the target" slightly.

The line of sight is crossed by the bullet. It is crossed soon after it leaves the muzzle, the distance depending largely on the distance of the sights used, above the center of the barrel. The bullet crosses above the line of sight, and drops to a point that should intersect with the intended point of impact. IOW, if you want to sight in at 200 yards, the line of sight and the bullet drop should intersect at that distance.

If the bullet drops below the line of sight ( crossing a second time) before 200 yards, the bullet impact will be low.

Jim

 

[JohnKielly]

You need also to verify how accurate the MOA adjustments on your scope are. You can check that by changing your elevation at a target at a precisely measured distance (100 yards for example).

 

[ttfreestyle]

Changing to the Nf and your AB data working like it should answers your question about the Leupold. Not all scopes track as they should.

 

[dstoenner]

The line of boresight is not crossed. The bullet, as it leaves the barrel starts dropping (due to gravity) and can't cross the line of boresight. The exact center of the bore will be slightly above the exact center or the intended point of impact on the target, the amount depending on the distance from the muzzle. This is why experienced boresighters will elevate the "boresight of the target" slightly.

The line of sight is crossed by the bullet. It is crossed soon after it leaves the muzzle, the distance depending largely on the distance of the sights used, above the center of the barrel. The bullet crosses above the line of sight, and drops to a point that should intersect with the intended point of impact. IOW, if you want to sight in at 200 yards, the line of sight and the bullet drop should intersect at that distance.

If the bullet drops below the line of sight ( crossing a second time) before 200 yards, the bullet impact will be low.

Jim

You are right that i used the wrong term. I was trying to say that the line if sight and the line of bore sight that you would see with a laser chamber guide would cross at around 25-35 yards.

i also thought about the second cross of the bullet. There are 2 cases commonly in use

1) you sight in at a longer distance that gives you a max effective range. Here the bullet stays within a defined killing area for an effective kill. In this case if the animal is closer than the sight in range no second crossing. If at the max effective range you get a second crossing with some drop

2) target shooting where you always adjust the elevation to compensate for drop. Here the second crossing in a perfect world is on the target face.

David

 

[Flatfishhunter]

The line of boresight is not crossed. The bullet, as it leaves the barrel starts dropping (due to gravity) and can't cross the line of boresight. The exact center of the bore will be slightly above the exact center or the intended point of impact on the target, the amount depending on the distance from the muzzle. This is why experienced boresighters will elevate the "boresight of the target" slightly.

The line of sight is crossed by the bullet. It is crossed soon after it leaves the muzzle, the distance depending largely on the distance of the sights used, above the center of the barrel. The bullet crosses above the line of sight, and drops to a point that should intersect with the intended point of impact. IOW, if you want to sight in at 200 yards, the line of sight and the bullet drop should intersect at that distance.

If the bullet drops below the line of sight ( crossing a second time) before 200 yards, the bullet impact will be low.

Jim

So, I zero at 100 yards. I don't change the elevation of the scope, and when I shoot at 200yds, my bullets impact 1/2" high. Would this mean that the first crossing is at 100 yards? Is there some way to adjust a scope so that the second crossing is at 100 yards (if this is your zero range)?

 

[SSL]

Try sighting zero at 25 yards. That's the distance most traditionally figure to be first line of sight crossing to be close at 100. Probably be a little low at 200. No such thing as the perfect do-all zero.