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Location: Texas
Joined: 08/13/2009
Posts: 37
Is my scope perpendicular?

Every time I try to push my rounds out past 300 yards I have to make windage adjustments. The further out I go the worse the problem gets even though there is no discernable wind.

If you have ever had this problem, or if you just want to know if your scope is mounted correctly you should read this article.

http://www.longrangehunting.com/articles/reticle-perpendicularity.php

WesternHunter's picture
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Joined: 05/05/2006
Posts: 2368
Is my scope perpendicular?

Don't know. I sure as heck don't buy that theory about Coriolis Effect coming into play though. Any distance within rifle range is just way too small of a scale for Coriolis to affect anything. Maybe a lot just has to do with the barrel itself and other factors, human, and mechanical. Don't know.

Offline
Location: Texas
Joined: 08/13/2009
Posts: 37
Is my scope perpendicular?
WesternHunter wrote:
I sure as heck don't buy that theory about Coriolis Effect coming into play. Even 1 mile is too small of a scale for Coriolis to affect much if shooting adjacent to the rotation of the Earth. For sure you would not see any affect when shooting parallel to the Earths rotation. Maybe a lot just has to do with the barrel itself and other factors, human, and mechanical. Don't know.

The coriolis effect only comes into play for extreme long range target marksmen, snipers (trying to make a head shot at 1000+ yards), or Navel gunners and such. For snipers a 1760 yard shot fired in a due north direction you would just add .3 mil easterly lead. It gets a little more complicated for east or westerly shots… it effects time of flight and you are getting into some serious trigonometry. During my time as an instructor we would touch on it for about 15 to 20 minutes then hand out the formulas. It never used to be an issue but with rounds that will actually reach out to a mile or better it’s becoming more of a detailed block of instruction from what I understand.

Offline
Location: Misouri
Joined: 11/30/2005
Posts: 365
Is my scope perpendicular?

Sugestion: Set this rig up inside out of the wind. Hang a piece of string weighted on the end. Put your gun on a good solid bench rest. Put a small level on the gun and make sure its properly level (Scope caps). Then match the crosshairs with the hanging string. Is it canted? If not make adjustments.

9 times out of 10 the issues your having are the indian not the arrow. For shooting itty bitty group off a bench make your adjustments. For hunting big game at your comfortable distances, hold and squeeze.

Best of luck and my 2 cents

Offline
Location: Texas
Joined: 08/13/2009
Posts: 37
Is my scope perpendicular?
remington wrote:
Sugestion: Set this rig up inside out of the wind. Hang a piece of string weighted on the end. Put your gun on a good solid bench rest. Put a small level on the gun and make sure its properly level (Scope caps). Then match the crosshairs with the hanging string. Is it canted? If not make adjustments.

9 times out of 10 the issues your having are the indian not the arrow. For shooting itty bitty group off a bench make your adjustments. For hunting big game at your comfortable distances, hold and squeeze.

Best of luck and my 2 cents

I don’t really like to argue with someone’s methods of setting up their own rigs but I can see several things wrong with this one.

1. You can NOT level a rifle by putting a level of any size on the scopes turret cap. If the scope itself is not already perfectly perpendicular to the rifle then you will be leveling the scope but offsetting the rifle.

The best way to level your rifle is to remove the scope and place the level on the front bottom ring. Another way is to remove the butt plate and use the 2 screw holes as your vertical line… this is the most commonly used method by military personnel.

2. Hanging a plumb line off the front of the scope will only work if you have the attach point in perfect congruence with the top of the vertical crosshair. However; if what you meant was to hang a plumb line from another object and then point your rifle in that direction… that will actually get you close.

But… as with every rule, there are exceptions. If you are hunting at ranges less than 200 yards and you zero your rifle for 100 yards, you shouldn’t have any problems. If you are hunting “critters” at longer ranges and want to improve your first shot hit rate then I would read the article and follow the instructions.

Now… I would say that this is just my 2 cents worth or just my opinion however; this is actually a variation of a method I taught during faze one of training during my time as an instructor at Ft. Benning.

Offline
Location: Misouri
Joined: 11/30/2005
Posts: 365
Is my scope perpendicular?

Its not my method its a sugestion. Maybe I'm confused by your question and after having re-read it several times realize that it wasnt a question. The weighted line was to be hung several yards in front of the gun. Its a good field expediant if the shtf. .ie scope goes down in the field, airline fubar it, ect..

I dont set up my own sniper rigs, I have my smith do it. It's a liablity factor for me. I'm not the best wind reader in the world but can keep it Minute of Felon well out of LE Sniper range.

Best of luck

Offline
Location: Texas
Joined: 08/13/2009
Posts: 37
Is my scope perpendicular?
remington wrote:
Its not my method its a sugestion. Maybe I'm confused by your question and after having re-read it several times realize that it wasnt a question. The weighted line was to be hung several yards in front of the gun. Its a good field expediant if the shtf. .ie scope goes down in the field, airline fubar it, ect..

I dont set up my own sniper rigs, I have my smith do it. It's a liablity factor for me. I'm not the best wind reader in the world but can keep it Minute of Felon well out of LE Sniper range.

Best of luck

Laugh Laugh Laugh Laugh
Minute-Of-Felon I've never herd that one before. Thats really funny.

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