Discussion in 'Technical Articles - Discussion' started by ADMIN, Mar 27, 2008.

# Reticle Perpendicularity

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2. ### wayneborngesserActive Member

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That was an excellent article! I have often watched my favorite FFL dealer mount scopes, gratis, for his customers and asked him how he knew whether or not the reticle was exactly horizontal and vertical. The customers got exactly what they paid for! It was "eyeballed" to perfection. I used a workmate, a level on the top of the action to get the gun perpendicular(?) and hung a weight on a string from my garage door, sort of a poor man's plumb bob. Do you think that is accurate? I did not think of your way as it seemed better to try to be as precise before going out and shooting. Any thoughts would be appreciated as I am going to be installing a new scope on my newest rifle within the next few days. I was even thinking of using an Archimedes type level arrangement to get the gun even closer to perpendicular. Again, any thoughts would be appreciated.

3. ### candersonWell-Known Member

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Reticle Perpendicularity

Great article. Have not tried Mr. Holland's method. I have purchased a reticle leveler from NECO industries. It is a machined two piece aluminum apparatus with a machined slot and a level. The level is placed on the barrel and the objective end of the scope. The gun is then inserted in a vise on sand bag and the reticle is compared to a plumb bob line or a vertical line on a wall. This seems to put the barrel and the scope in the same plane, then the reticle can be adjusted to be parallel with the barrel/scope axis. Just curious on any thoughts or comments about this method. It has worked for me out to 400 yds.

4. ### guns_and_labsWell-Known Member

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Good article, thank you. The method described will allow me to test a theory that I need a naturally canted reticle. It seems, when I use one of the reticle devices, that the reticle is not plumb when I actually set the rifle up to shoot -- that my natural position is slightly canted -- all measured by whether the leveled target appears to align with the reticle. Now I can test that easily with Mr. Holland's test.

One question: how often is a person's natural position such that a canted reticle is necessary?

5. ### ba19500Well-Known Member

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I've used a Unertl 15X Ultra-Varmint for years. There is no vertical adjustment. I wonder how accurate their fixed method is? Pretty good I'll bet.

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What about using the "Level-Level-Level" to do this?

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Reticle Perpendicularity

Gentlemen,

Thank you for the comments on the article.. I'm glad the information has helped some of you!

Most shooters never see proper scope mounting. Often times gunsmiths/store clerks do a quick and dirty job of mounting your rifle scope. They do not give any thought to what they are doing with your expensive rifle/scope combination.

The scope bases need to be level with one another. One can use a precision straight edge to check this and machine/shim the bases until they are flat/level with one another. Receiver tolerances can be out quite aways...

Once this is done, mount the ring halves providing the maximum support for the scope tube ensuring proper eye relief. Use a lapp to lapp the ring halves to at least 75% contact with the lapp. I use a water soluable lapping compound that is available at most automotive stores, it cleans up easier. Once the rings are lapped and mounted/tighhten to 65 inch pounds, I use Mark 4 style rings, we then level the base in the vise.

I use a Starrett precision machinists level to level the scope base and hang a plumb bob across the shop to align the reticle. Tighten the ring caps evenly checking the reticle as we do so.

This gets us VERY close, we then use the method described in the article to fine tune the reticle. One reticle perpendicularity is achieved it is DONE. Gremlins do not reside in the scope making changes to the reticle while you sleep.

Yes, we see alot of shooters who cant the rifle. The easiest cure is to purchase a scope level and mount it on the scope tube ( do so when we are making the reticle plumb with the rifle in the vise) This is a great truth detector and will aid you in long range shooting. If Len okays it, I'll do an article as to the effect of reticle cant at long range.

Holland Tech Tip #409 When hunting in rough mountainous country it can be hard to determine if the reticle is plumb. Trees grow plumb most of the time and can be used to check reticle perpendicularity before making the shot.

Thanks for the opportunity to share our knowledge.

Be safe and shoot straight!

Sincerely

Darrell Holland

8. ### wayneborngesserActive Member

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Thank you, glad to know the background of your method! Always helps to know the reasoning, as well as the background behind a method.
Thanks again.

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Reticle Perp.

Dear Wayne,

You are welcome, now go forth and do GREAT things with your rifle. Always watch for the wind, gravity is a constant, its the wind that usually bites our backside!!!

Good luck,

Darrell Holland

10. ### MikecrWell-Known Member

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This is a great approach to achieving true tracking(which is what matters) for all of us who dial in elevation. Very easy to do.

After verifying a new scope tracks true vertically(as described), I can move it from rifle to rifle and mount it level without looking through the scope at all. Just levelling the turret top to the level rifle on my bench. The 'level rifle' being the only trick.
I have done this many times with my 'reference' scope.

ALso, one thing I have validated GH hunting in hilly PA; You cannot judge true level.
An installed ScopeLevel is a must.

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Mikecr

Dear Mike,

Imagine the potential if youused the same mounting system on ALL your rifles. ( I like the Picatinny rail and MK. 4 rings)

You can plumb the scope in one set of rings and change from rifle to rifle with the same repeatability!

We can have a high magnification scope for load developement and exchange for our hunting scope in a matter of seconds.

Give it some thought, you may find it as useful as I have???

Best of luck in your shooting endeavors...

Sincerely

Darrell Holland

12. ### jwp475Well-Known Member

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David Tubbs advocates canting the rifle and plumbing the reticle. He mounts his scope so as that the reticle is plumb with the rifle canted and Mr. Tubbs maintains that by moveing the scope to ones eye rather than moving ones head, provides for a more ridgid lock up

13. ### woodsWell-Known Member

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Mr Holland, wish I had found your article earlier and then I wouldn't have had to work through it myself. I have a 300 win mag with a Kahles MultiZero and experienced the rotational symptoms you talked about

so I made myself a crude sketch and figured out that when cranking for elevation the crosshairs were actually traveling along a divergent line and cause the problem

the reticle moves along line A which would cause you to raise the rifle to point G and when you move the point of aim to center it would actually move the POI to point H and thus along line D. I solved this by slight scope rotation just as you suggest.

That started me thinking about cant and eventually I got the level-level-level and an anti-cant bubble for the scope

What do you think about the EXD device? EXD ENGINEERING VERTICAL RETICLE INSTRUMENT at Brownells

Someone mentioned David Tubbs cants his rifle. That's and understatement!

Last edited: Aug 31, 2008

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Reticle Perpendicularity

Gentlemen,

The Tubb method of rifle canting is used more in the Hi-Power world. The canting of the rifle is achieved by raidial holes drilled and tapped in the receiver. This allows the sight/scope to still be perpendicualr to the bore. Once offest in this fashion the level is installed to maintain the same relationship when mounting the rifle. Again this is used mostly in the Hi-Power world and is not practical in a hunting rifle as the mount holes are drill on center/perpendicular to the receiver in virtually all production rifles. The Tubb 2000 is the ONLY rifle that I'm aware of that offers this feature.

Occasionally we will see a competitor using a canted scope and rifle, he must adjust elevation and windage to shoot at a specified range. This is not practical nor reccomended for the hunter.

Congrats to the gentlemen who used our method to adjust reticle perpendicularity on his Khales rifle scope, nice photo's and diagrams. I wish I were that handy with a computer?

Give some thought to attending our long range shooting schools next year, you'll have a great time and come away a better shot.

Thanks again for the opportunity to share our knowledge on long range shooting.

Sincerely

Darrell Holland