What do you use to level the reticle?

KY_Windage

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Sorry. Post 185
If that is all you do, you have no clue whether your scope is on straight (meaning in line with the bore) or not. It really does not matter out to 250 yards. Only if you try to crank up for 500 yards or more will it matter. I don't know how to explain this any better than I did in Post 214.
 

OFFISHN

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If that is all you do, you have no clue whether your scope is on straight (meaning in line with the bore) or not. It really does not matter out to 250 yards. Only if you try to crank up for 500 yards or more will it matter. I don't know how to explain this any better than I did in Post 214.
KY-Windage I agree. If only worried out to 250 possibly 300 yards put it where you like it and have fun. Past that yardage I agree a tall target test is the best way to confirm or know your off a little bit. I believe the guy was asking how to initially set it close to the bore. Like in my post I level the action rails then level the cross hairs with a plumb bob and flash light. Just my method. Many have others. Enjoy and shoot straight.
 

Bart B

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How many degrees of error is allowed twisting the scope in its rings to align the vertical reticle wire plane/axis to the bore center below the scope?
 

fiftybmg

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How many degrees of error is allowed twisting the scope in its rings to align the vertical reticle wire plane/axis to the bore center below the scope?
Any error will cause a shift to POA if you dial or holdover.

According to those who understand the math, if you are canted 3 degrees and dial for 1000 yards with a .308, you will induce 24 inches of windage. I haven't done the calculation myself, but this seems a reputable source of information :

https://www.shootingillustrated.com/articles/2016/3/28/rifle-scope-reticle-cant/

That's 8 inches windage error per 1 degree cant at 1000 yards. Your eye can't recognise one degree reticle cant in the scope, it's too fine a measurement.

Note that if you aim scope center, and do not holdover or dial, you do not induce a windage error, so if you aim dead on, you do not need to worry about the reticle cant.

That is why the tall target test is so important for long range shooting, you can measure the distance of the holes to vertical, and calculate exactly how much cant you have. If you are unable correct it, you can at least factor it in to your data.

I'm not a fan of twisting the scope in the rings on the range to try make corrections to the tall target test, nobody can measure one or two degrees with their fingers.
 
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Bart B

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The formula for horizontal impact shift from cant is:

Bullet drop at target range X sine of the cant angle:

Example for 308 Win at 1000 yards with a 1 degree cant: 400" X .01745 = 6.98" The line of fire moved that far to the right 400 inches above the point of aim.

Yes, there's a tiny bit of vertical drop. It's the difference between 400" and 400 X cosine of 1 degree. About .061 inch
 
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KY_Windage

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I'm not a fan of twisting the scope in the rings on the range to try make corrections to the tall target test, nobody can measure one or two degrees with their fingers.
But there is simply no other way to get it set exactly right. As I said, it is a "trial and error" exercise. But, with a little practice, most people can get it perfect by the third or fourth try.

That takes about half an hour, and I'm probably going to leave that scope there for years. To me it is a very small price to pay for exactness.
 

Hand Skills

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One little trick I discovered with the flashlight method;

If the gun is a bolt action, it's possible to remove the bolt and look down the bore. In so doing, one can view the projection of the reticle THROUGH the bore.

Once my eye is aligned with the bore it's pretty easy to adjust the scope in the rings until the projected reticle PERFECTLY bisects the bore.

Thats the best way I've found to ensure the reticle is COINCIDENT with the bore. 100% optical alignment. No levels or plumb bobs or anything. Just adjust the scope until the line on the wall divides the bore into 2 perfect halves.

Unfortunately, this only works with scopes that have a full vertical crosshair. It does not work with some BDC reticles that leave the top half of the reticle open...
 

Bart B

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I've marked lines on front sight levels for 1 degree cants. Shooting 1000 yard team matches, when the coach says "right 1 MOA" for me to make that change on the rear sight, I would cant the rifle to move shot 10 inches right, then shoot. A "cant card" on the ammo box listed angles for different ranges and loads for a 1 MOA change.
 

Mram10us

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Leveling the action and reticle with a plumb line will definitely get you close. I did a tall target test yesterday at 100yds. Shot a 300 rum and 6.5-284 at the bottom “+” then ran it up 5mil then 7 mil. I was 1/16” off to the left with the rum, which I don’t care because spin drift will negate that. The 6.5-284 was 1/16 right. Why not do the TTT and take out another variable?
 

fiftybmg

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An update on the two flashlight method.

A plumbline is not necessary.

I swapped scopes this week, and after I trued it to the bore, I realised that the plumbline is completely unnecessary. I'll update the instructions with new pictures when I get some time this week.
 

OFFISHN

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:):):):):):)
An update on the two flashlight method.

A plumbline is not necessary.

I swapped scopes this week, and after I trued it to the bore, I realised that the plumbline is completely unnecessary. I'll update the instructions with new pictures when I get some time this week.
Interested :)
 

fiftybmg

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I levelled my son's 308 Winchester this way, and he consistently hit steel at 1200 meters.

My max distance for consistent hits on steel is 500 meters.

The result of the exercise is not perfect alignment, but close to perfect, so that the induced windage is minimised at long range and can be compensated for with a few clicks.
 

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