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Rifle Scopes using a plumb line to align the scope

E

emmagee

Private
Minuteman
May 21, 2004
93
0
56
Texas
Once you have properly leveled the rifle, I have always round using a plumb line is the best way to align the reticle to the rifle. When aligning the reticle, does it matter what distance the plumb line hangs from the rifle?

At the house, I can pretty easily hang a line 20-25 yds. out, but to stretch it out to 100 yds requires a trip to the range. Is it a foolish endeavor to alight the reticle with the line hanging at 20 yds? Should it only be done when you can get the line out at 100 yds, give or take?

Thanks much!
 
Re: using a plumb line to align the scope

If you can adjust parallax enough to get a clear view of the line it will work, but it will work better at 100.

Many ways to do this have been posted on here. I would say the simpliest is to get a set of Feeler Gauges and use them between the bottom of the scope and the base.

The problem you may face with just using the plumb line is that the reticle may be canted in the optic. A box test will tell you exactly what is going on.

My way of doing it, Feeler gauges, verify with line, confirm all with box test. Granted the better quality of optic you are running the less you have to worry about, but im the type of guy that likes to double check stuff.
 
Re: using a plumb line to align the scope

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: emmagee</div><div class="ubbcode-body">Once you have properly leveled the rifle, I have always round using a plumb line is the best way to align the reticle to the rifle. When aligning the reticle, does it matter what distance the plumb line hangs from the rifle?

At the house, I can pretty easily hang a line 20-25 yds. out, but to stretch it out to 100 yds requires a trip to the range. Is it a foolish endeavor to alight the reticle with the line hanging at 20 yds? Should it only be done when you can get the line out at 100 yds, give or take?

Thanks much!</div></div> Use the corner of a house or the window frame of a building 100 yds away or farther if possible while using a small level on the base.
 
Re: using a plumb line to align the scope

Feeler gauges are your friend
 
Re: using a plumb line to align the scope

So this might be a silly questions, but whats the feeler guage for? I just dont see what it accomplishes.
 
Re: using a plumb line to align the scope

I was told the crosshairs and the bottom of the scope are not always perfectly parallel. Any truth to that?
 
Re: using a plumb line to align the scope

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mram10</div><div class="ubbcode-body">I was told the crosshairs and the bottom of the scope are not always perfectly parallel. Any truth to that? </div></div>

True they arent. But in the vast majority of quality optics the elevation turret and bottom will be level. When that is level to your rifle they it will track correctly. If you do this and your reticle isnt plumb or looks canted then you have a canted reticle.

It does you no good to have a plumb reticle with a optic that tracks untrue.
 
Re: using a plumb line to align the scope

Well that makes sense. Just wasnt thinking "stacking" them.
 
Re: using a plumb line to align the scope

Thanks for info, folks. I know about the feeler gauge method, but have never used it, guess I should give it a whirl. One question, though, it can only be used with a one piece base, correct? That usually isn't an issue, but I do have some rifles with two piece bases.

Thanks again!
 
Re: using a plumb line to align the scope

I usually set my rifle in secure bags and get it in the most comfortable position for firing. If you are <span style="font-weight: bold">slightly</span> canted it will not matter because you will be using a bubble to duplicate the cant.
I have a small diameter rope hung at 100 yards with a weight attached. I then carefully line up with the verticle and set my bubble. I then check to make sure the tracking is true, by running the impact up the verticle reticle(by actually firing the rifle). It will be very easy to tell if it is correct. Make sure to run it a ways up not just one or two mil.
 
Re: using a plumb line to align the scope

Orange extension cord with a rock tied to it hanging from a tree works really good.
 
Re: using a plumb line to align the scope

Good picture Tex! Im guessing once the feeler gauges are in place, and there is no "play" or "wobble" in the scope, its safe to tighten up the rings?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Texagator</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NatepNG</div><div class="ubbcode-body">So this might be a silly questions, but whats the feeler guage for? I just dont see what it accomplishes. </div></div>

You put them between the rail and the flat part on the underside of the scope. Use them to "shim it" and just barely squeeze in there and they will level your scope for you.

HERE is a picture I found with a Google images search that kinda explains it. </div></div>
 
Re: using a plumb line to align the scope

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jackalope33B</div><div class="ubbcode-body">Good picture Tex! Im guessing once the feeler gauges are in place, and there is no "play" or "wobble" in the scope, its safe to tighten up the rings?</div></div>


Tighten the screws lightly so the scope doesnt move front to back... then take out the feeler gauge and tighten to your inch/pounds recommended by your ring manufacture...

Hope this helps...
 
Re: using a plumb line to align the scope

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: T.C.</div><div class="ubbcode-body">Here is another way ...

Mike at CS Tactical made this scope mounting video but he uses levels and not the feeler gauge...

http://www.youtube.com/watch?v=lQgXPA4A2J0

</div></div>

Looks like im off to the auto parts store for a feeler gauge set
smile.gif
THANKS!!!!!!!
 
Re: using a plumb line to align the scope

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: T.C.</div><div class="ubbcode-body">Here is another way ...

Mike at CS Tactical made this scope mounting video but he uses levels and not the feeler gauge...

http://www.youtube.com/watch?v=lQgXPA4A2J0 </div></div>

What level is he using in this video on the top of the scope and where do you find this? I'm assuming he's using Wheeler level-level in the action. I know where the Wheeler is, but what other levels are out there?
 
Re: using a plumb line to align the scope

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: T.C.</div><div class="ubbcode-body">Here is another way ...

Mike at CS Tactical made this scope mounting video but he uses levels and not the feeler gauge...

http://www.youtube.com/watch?v=lQgXPA4A2J0 </div></div>

What level is he using in this video on the top of the scope and where do you find this? I'm assuming he's using Wheeler level-level in the action. I know where the Wheeler is, but what other levels are out there? </div></div>

Looks like one of the vial levels that you can get from McMaster Carr...they are less than 3 bucks a piece.

Style M Here
 
Re: using a plumb line to align the scope

Great thread, I think this will help with some of the frustration in the future.
 
Re: using a plumb line to align the scope

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: abersfelderami</div><div class="ubbcode-body">How accurate is a 1" long bubble level? </div></div>


Working with those style of bubble levels for the past 15 year I can say that they are anything but accurate. I use to level our robot test stands with a calibrated machinist level and then check these cheap plastic bubble levels from time to time and tossed many of them out. If you have 2 and they both read the same you should be good to go.

Also if you only have one you can place it on a surface then rotate it 180 degrees and if it read the same it should be fine.

Mac
 
Re: using a plumb line to align the scope

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cmacclel</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: abersfelderami</div><div class="ubbcode-body">How accurate is a 1" long bubble level? </div></div>


Working with those style of bubble levels for the past 15 year I can say that they are anything but accurate. I use to level our robot test stands with a calibrated machinist level and then check these cheap plastic bubble levels from time to time and tossed many of them out. If you have 2 and they both read the same you should be good to go.

Also if you only have one you can place it on a surface then rotate it 180 degrees and if it read the same it should be fine.

I like the feeler gauge method myself.

Mac
</div></div>
 
Re: using a plumb line to align the scope

Great thread, I'm going to be mounting my first long range scope next week, using some techniques from here. We'll see how it goes...
 
Re: using a plumb line to align the scope

I use a plumb line to align the buttplate screw holes vertical.

I then align the horizontal reticle wire with the siding on the home across the street. I've installed enough siding professionally to know that a professional lines up each lap perfectly horizontal with a level.

Done-ski!
 
Re: using a plumb line to align the scope

Guys, I would like to chime in here for a second.
It seems to me that if the scope to reticle cant is off an appreciable amount you will have either one or two issues:

If you use a plumb line and the gun is level you now have the reticle plumb to the bore. In this case as long as you used the holdover points and didn't touch the turrets you would be accurate. But as soon as you dialed the turrets any decent amount you would start to veer off your intended target(s).

If you level the scope to the gun as long as you were to use the center aiming point you could move the turrets as you would stay on track but if you used holdovers you would start to veer away from your inteded target(s).

Has anyone ever figured out which way would be better? Say if your reticle was 3 degrees canted, would you be better off to level using the plumb line or the scope to gun method? It seems to me that depending on the type of shooting you are doing that would be the deciding factor for which method of leveling you would use if indeed you had a scope that had some serious cant to the reticle.

Please bear with me on this. Some of you know me and know that I don't get to shoot a lot. I am always interested in the scope to the gun and shooter relationship though.

Thanks,
Paul
 
Re: using a plumb line to align the scope

The best method is...both. you need to determine if your reticle and turrets are indeed plumb. I recomend feeler guage method and check with a plumb line.

If you do both (scope body and reticle) and find them different, then you need to make the call as to which is more important.

I contend that the errector system being plumb is more important, but I typically dail elevation and hold wind.

In my case, its easy though, as my errector and reticle are plumb...thanks Paul.
 
Re: using a plumb line to align the scope

So what do you use when you have high scope rings? i put feeler gauges under my scope, and Im still shy about 1/3" or so..
 
Re: using a plumb line to align the scope

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cmacclel</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: abersfelderami</div><div class="ubbcode-body">How accurate is a 1" long bubble level? </div></div>


Working with those style of bubble levels for the past 15 year I can say that they are anything but accurate. I use to level our robot test stands with a calibrated machinist level and then check these cheap plastic bubble levels from time to time and tossed many of them out. If you have 2 and they both read the same you should be good to go.

Also if you only have one you can place it on a surface then rotate it 180 degrees and if it read the same it should be fine.

Mac
</div></div>

Also have a machinist background, though I'm an office bitch these days. Anyhoo, I agree, bubble levels are worthless. Somewhat worthy if two match. I had two I stole from a decent brand carpenter level and on an even and level surface I placed the two side-by-side and on the 2" vials, they were off by approximately 3/16".
shocked.gif


Then I borrowed a Mitutoyo digital protractor/level and use that instead. Then I followed up with the plumb line and on my SWFA 5-20x50 the crosshairs were plumb and the tracking was spot on as well. That's the far extents of travel from topping out to bottoming and back to center.

I liked the digital protractor so much that I went in search for one online and found them for $200. Being as frugal (cheap) as I can be, I opted for the "cheap" one they have at Sears. A Craftsman. I tested it against the Mitutoyo and the farthest off it came was within 0.10 degree. I dubbed that good enough for me.

Here's the cheap azz product I speak of... http://www.sears.com/craftsman-digital-torpedo-level/p-00948295000P
 
Re: using a plumb line to align the scope

I level my reticles with a plumb bob at 100yards. On the last scope I mounted (a NF F1), after leveling the reticle via the plumb bob, I decided to run the elevation turret up and down to check the reticle travel. There was a difference, they were not in the same plane ( my guess is a degree or two). Since I mostly adjust elevation the scope was rotated so the elevation travel was plumb, not the reticle. In hindsight I could have split the difference, but I think at this point it is Matter of splitting hairs.

I would bet this is present in most scopes and probably really has little to no effect on anything, It is just interesting to note. This is my two cents,YMMV!
 
Re: using a plumb line to align the scope

Personally, I'd send that scope back. If the reticle is really canted 2 degrees, that will cause error at long range. For example, if you need 10 mils to get to 1000 yds it'll introduce just over a foot of lateral error.

If you level to the turrets and shoot that way, there will be no error of course. But it's difficult mentally to shoot with the reticle canted with the world as your eye and your training naturally tries to make it verticle.
 
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