Plumb line distance when mounting a scope?

[randello88]

Hi everyone, i have always used the flaslight method, confirming later using house walls at a distance to make sure the reticles of the scopes of my hunting rifles were mounted straight to gravity.

Now i moved to a new house and i can place a plumb line 20 yards away when mounting the scope. I read on forums that a 100 yards plumb line is better. Why is that? As long as i can focus the rope at 20 yards (my NF has parallax adjustments), shouldn't the process be as accurate as hanging the rope at 100 yards?

Am i missing something?

Thanks!

 

[6.5SH]

I'd guess that the 100 yard advice is for scopes without a parallax adjustment.

 

[Taylorbok]

I used to do it in my garage 30' and that wasn't enough, I'd still find cant in the system during a tall target test.
I think it was to hard to distinguish if the rope and reticle were actually parallel.
I started doing it at 100 because that's the distance my range is and seems to be working perfectly, I don't know what distance you can come into and still have success.

 

[redneckbmxer24]

I’ve never had a problem doing this at 30’ with a few feet of paracord. Square is square.

If you’re doing a tall target test testing tracking after squaring the reticle and getting error in that then your reticle probably isn’t perfectly square in the optic.

 

[Taylorbok]

I’ve never had a problem doing this at 30’ with a few feet of paracord. Square is square.

If you’re doing a tall target test testing tracking after squaring the reticle and getting error in that then your reticle probably isn’t perfectly square in the optic.

Same optic shoots perfectly vertical after being leveled at 100 yards.
Like I said, it seems easier to make a small error on truly plumb at the closer distances.

 

[randello88]

Same optic shoots perfectly vertical after being leveled at 100 yards.
Like I said, it seems easier to make a small error on truly plumb at the closer distances.

How is that? Unless you don't have parallax adj it doesn't make sense to me

 

[Taylorbok]

How is that? Unless you don't have parallax adj it doesn't make sense to me

I can't explain it just reporting my finding since you asked. Do you test your level with a tall target?

 

[randello88]

I can't explain it just reporting my finding since you asked. Do you test your level with a tall target?

I will after the installation. I did a preliminary test with a paper target and putting the scope in a vice, it tracked truly to the reticle

 

[Baron85]

I do it at around 5‘ on a door. I hang the plumb line over the door so it gets pinched when I shut the door. I mount my rifle to a tripod or bipod and bag if you don’t have a tripod with the butt of the gun facing the plumb line. Level the rifle, mount the scope loose so I can spin it. Turn off all the lights and use a flashlight through the front of the scope so the reticle is projected onto the door and rotate the reticle to match the plumb line. You will have to move the rifle around to get it to line up with the plumb line.

This is the best method I have found to be able to do it at home before going to the range.

I have never done a tall target test but haven’t had issues hitting targets at distance.

 

[Edsel]

I do it at around 5‘ on a door. I hang the plumb line over the door so it gets pinched when I shut the door.

FORTUNATE IS HE WHOSE BUBBLE LEVELS ARE IN HARMONY WITH EACH OTHER

- Sun Tzu, at the signing of the Declaration of Independence, 1776

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You don’t say

 

[Baron85]

Yeah, just like that!!! That’s funny.