Plumb Bob for Aligning Scope

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Sorry I edited it like a thousand times to try to make it more clear what im trying to say.

So would it be right in saying you don't really need a level at the pic rail with the mirror method in order to line up the scope vertical retical line with the center line between the scope center and the barrel center?

Did someone mention earlier that AFTER using the mirror method you can check the level on pic rail by lining up the retical to a plumb Bob that was started in this thread, then look at the level and if it is not correct then either the level is wrong, how it is placed is incorrect, or something is skewed?

Allen
 
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DBlue said:
I got tired of fooling around with small plumb bob's always moving with the slightest breeze while trying to align my scopes. I machined a large plumb bob out of 2" diameter solid aluminum round bar and that took care of the problem....got all my scopes aligned today and it does make a difference, especially when going from 50 yards to 100 yards and further...:)

View attachment 384920

View attachment 384921
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Healthservices said:
Sorry I edited it like a thousand times to try to make it more clear what im trying to say.

So would it be right in saying you don't really need a level at the pic rail with the mirror method in order to line up the scope vertical retical line with the center line between the scope center and the barrel center?

Did someone mention earlier that AFTER using the mirror method you can check the level on pic rail by lining up the retical to a plumb Bob that was started in this thread, then look at the level and if it is not correct then either the level is wrong, how it is placed is incorrect, or something is skewed?

Allen
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Allen,
As I understand the process, leveling the gun or the pic rail is irrelevant.

Step one: align reticle (vertical line) with barrel bore using the mirror as shown in the photo.
Step two: which is using the plumb bob only matters if you will be using a shooting level, attached to scope or pic rail/ dove tail. If not installing a level on the scope preferably then there is no use for the plumb bob.

Step one removes scope cant and once set stays set.
Step two by using a scope mounted level set to the reticle, allows the shooter a visual reference (the bubble) to be able to hold the gun true at each shot.

Hope this helps

OP: very nice plumb bob.
I have only recently begun using the mirror and plumb bob method and tied a piece of string to 2" wide strip of lead sheet rolled up into a 2 1/2" coil. It works AND its's real pretty... well it works!
 
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starlingassn said:
get a mirror,


set it up at say 5yds,
set your scope to 10 yds (or when its focused in the mirror)


look through the scope at your reflection in the mirror (a steady gun rest helps)

loosen the scope ring screws and rotate the scope till the vertical crosshair intersects the center of the bore when the crosshairs are centered on the scope objective.

"bam" your crosshairs are now aligned with the bore

snug your ring screws and recheck,
repeat till perfect :cool:


then use the plumb line to get your vertical line,
adjust and lock down your scope level,

now everything is lined up and if you miss its your own fault LOL

View attachment 384934
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I just checked my set up using this method and it looks good as far as my eye can tell..lol. Being this is just an eyeball technique I don't really see the precision with it? Or is it just supposed to be a close is good enough thing?
I set my scope with a level on the pic rail, then aligned the vertical reticle to a plumb line drawn on paper at 40 yards. Then I aligned the scope level with that.
Anyway, it's all good from my eyes perspective.
 
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superchikn said:
Allen,
As I understand the process, leveling the gun or the pic rail is irrelevant.

Step one: align reticle (vertical line) with barrel bore using the mirror as shown in the photo.
Step two: which is using the plumb bob only matters if you will be using a shooting level, attached to scope or pic rail/ dove tail. If not installing a level on the scope preferably then there is no use for the plumb bob.

Step one removes scope cant and once set stays set.
Step two by using a scope mounted level set to the reticle, allows the shooter a visual reference (the bubble) to be able to hold the gun true at each shot.

Hope this helps

OP: very nice plumb bob.
I have only recently begun using the mirror and plumb bob method and tied a piece of string to 2" wide strip of lead sheet rolled up into a 2 1/2" coil. It works AND its's real pretty... well it works!
Click to expand...
Just draw a plumb line on a piece of paper using a level and a sharpie, then you don't need a plumb bob swinging in the breeze. I do this at the 40 yard target box.
 
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It seems to me that the best way to do this would be by using the mirror and two plumb bobs. Hang one plumb bob in front of the mirror and hang a second from the muzzle of the rifle in line with the bore then line the two up through the scope and you'll have the crosshairs and the bore in perfect alignment.

You could probably just use the one hanging from the muzzle, but a second won't hurt.
 
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superchikn said:
But then I would have to draw a plumb line on all the squirrels and pigeons I shoot.
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Not really, they already drew a horizontal line, you just have to aim your cross hair between them.

giphy (1).gif

🤣

Allen
 
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And for those that assume their scope is perfectly centered and square with the barrel how many of you have a BSA? Do you use their special scope rings or just the standard 11mm rings you get from Amazon?

Are you aware the bsa dovetail is not the standard 11 mm dovetail? Many of the BSA dovetails are a wider 13 mm!

So what does that mean? It means if you use a standard 11mm scope ring on a BSA with a 13mm dovetail the scope will be off center more to one side rather than centered over the barrel. And in the picture below it actually can tilt the scope ring to one side as well.

20240113_182307.jpg

Maybe you should take a look!

And using one of those fancy aluminum scope levelers that fit between the scope base and the scope rail will only make the bottom of the scope rail parallel with the dovetail. It will still be off to one side.

Will looking through the scope using the plumb Bob string make the scope vertical line bisect the barrel down the centerline in this case? Uh.. don't think so.

Here is a scope ring made just for the BSA dovetail mounts. They mention how wide the BSA dovetail is.

Thread 'Adjustable Scope Rings for BSA' https://www.airgunnation.com/threads/adjustable-scope-rings-for-bsa.1304115/

And please I'm not trying to argue, I'm just trying to show why looking through the scope at a plumb bob is not what some assumed it to be. If im wrong please show me. I can be, and am wrong many times, just show me so I can learn too.

I want to be better too.

Allen
 
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Healthservices said:
Oh so I looked at the picture I just shot and it looks like I may have the clamp upside down. 🤪

View attachment 425084
Yup. 😞

Although no longer tilted, because it is made for a 11mm dovetail it is biased to the left more than the right.

Sorry but had I mounted the scope the other way it would have been more off.

Allen
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It doesn’t really matter if the scope is mounted off-center, so long as the reticle aligns with the center of the bore and the reticle is plumb. You’ll just have to hold the rifle canted one degree or so, something most of us probably do inadvertently anyway.

You could mount the scope 90 degrees offset and so long as you held the rifle horizontally your point of impact and holdovers would still work fine. Think of the USFT and how the grips on many of them were angled 45 degrees or so to the side.
 
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Sawney Bean said:
It doesn’t really matter if the scope is mounted off-center, so long as the reticle aligns with the center of the bore and the reticle is plumb. You’ll just have to hold the rifle canted one degree or so, something most of us probably do inadvertently anyway.

You could mount the scope 90 degrees offset and so long as you held the rifle horizontally your point of impact and holdovers would still work fine. Think of the USFT and how the grips on many of them were angled 45 degrees or so to the side.
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Well the reticle center point is always aligned to the center of the bore no matter where it is. But is the vertical centerline of the retical aligned to these two points? Using the mirror method will get you there. Using the plumb bob will not always give you that because assumptions are made.

Allen
 
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Remember this picture with the scope moved over to the left of the bore? The scope retical vertical is not lined up with the center of the bore, yet using the plumb bob the scope sees the plumb bob correctly. if that distance is the only distanced you will ever shoot, you are good. but if not cant will be a issue.

Screenshot_20240108_195448.jpg

if you use the mirror method even though the scope is to the side you will see that you are off and will have to rotate the scope in the rings so everything will line up. At that point your retical finally correct.


Allen
 
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Sawney Bean said:
....

You could mount the scope 90 degrees offset and so long as you held the rifle horizontally your point of impact and holdovers would still work fine. Think of the USFT and how the grips on many of them were angled 45 degrees or so to the side.
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If you mounted the scope 90 degrees to the bore, you still have to hold the gun perfectly at that same 90 so you don't introduce cant. Even then then the scope must be rotated till the retical is phased correctly with the center of the bore right?

Allen
 
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Healthservices said:
If you mounted the scope 90 degrees to the bore, you still have to hold the gun perfectly at that same 90 so you don't introduce cant. Even then then the scope must be rotated till the retical is phased correctly with the center of the bore right?

Allen
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Exactly. So in the picture you posted earlier, even if the BSA dovetail results in the scope being offset, all you need to do to compensate for it is align the reticle with the center of the bore and hold the rifle so that the reticle is plumb. This means the rifle itself will be slightly canted, but I doubt many shooters could detect it. Basically instead of rotating it 90 degrees you're rotating it one or two degrees.

Alternately, you could zero it with the point of impact offset an equal distance. I used to do that with old eastern bloc optics. The old soviet scopes and red dots used to sit about an inch to the left of the bore, so I would zero rifles with them to hit about an inch to the right of the point of aim.
 
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