New Posts New Posts RSS Feed - physics of level scope reticles
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Check GunBroker.com for SWFA's No Reserve and No Minimum bid firearm auctions.

physics of level scope reticles

 Post Reply Post Reply   Topic Search Topic Search  Topic Options Topic Options
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/13/2009 at 16:22
jetwrnch View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: July/03/2006
Location: Knoxville, TN
Status: Offline
Points: 294
Thought I'd bring this into a new thread instead of hijacking the other one. My reasoning on thinking that it's more important to have the scope level to the Earth than the bore is that the verticle crosshair is always verticle to gravity. If the bore is slightly off to one side it will affect windage to some degree depending on distance and scope heigth over bore. If the scope is level to the bore but the shooter cants the rifle then both windage and elevation will be off. Between the two I would think that elevation is the bigger variable all things being equal. My thought is that for hunting you'd want the rifle to shoulder with the crosshair as verticle as possible without having to re-adjust. I agree that for target or precision long range shooting the goal is to have the verticle crosshair aligned with the bore and prependicular to gravity. I don't know that a SLIGHTLY canted crosshair does any more harm than parralax error. Parallax? paralax, par...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/13/2009 at 18:18
Monster View Drop Down
Optics Master
Optics Master
Avatar

Joined: December/16/2008
Location: So. Cal
Status: Offline
Points: 2031
I think your reading to far into this........

Are you asking a question or just adding a remark?


Edited by Monster - May/13/2009 at 18:18
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/13/2009 at 18:20
rifle looney View Drop Down
Optics Master
Optics Master
Avatar

Joined: November/21/2008
Status: Offline
Points: 2553
           Thinking
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/13/2009 at 19:14
sakomato View Drop Down
Optics Master
Optics Master
Avatar

Joined: February/28/2008
Location: Houston
Status: Offline
Points: 1085

It is important to shoot with a reticle that is level.  If the rifle is canted then that is of such minor importance as to be negligible.  Evidence this rifle used by David Tubbs with a cheek-over hold

 
the rifle bore ends up in line with the scope when the scope is level.  He shoots lights out and the gun was banned from competition.
 
If you shoot with a reticle that is a little off then this will be the effect
 
 
this is a target shot at 100 yards while cranking elevation on the turret.  It was where I discovered the importance of a level reticle and the fact that I naturally held a rifle at a cant.  I am retraining myself to hold level with the anit cant devices on my scopes.


Edited by sakomato - May/13/2009 at 19:16
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/13/2009 at 19:22
John Barsness View Drop Down
Optics Optimist
Optics Optimist


Joined: January/27/2009
Status: Offline
Points: 785
Which is why many scopes are blamed for elevation adjustments that include a "horizontal" tendency, when the error is really due to scope mounting and/or the shooter canting the rifle.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/13/2009 at 19:29
jetwrnch View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: July/03/2006
Location: Knoxville, TN
Status: Offline
Points: 294
Stating my opinion so folks can set me straight. I have literaly spent hours trying to get crosshairs level. I've used LASERs, a Level Level Level, etc. The reticles never look right. I'm assuming it's my eyes causing the reticle to look canted when it isn't. I've found that even good scopes may not have the reticle square with the adjustment caps. Now factor in reticles that don't have straight lines, i.e dot scopes. Sheesh!

Edited by jetwrnch - May/13/2009 at 19:30
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/13/2009 at 19:54
sakomato View Drop Down
Optics Master
Optics Master
Avatar

Joined: February/28/2008
Location: Houston
Status: Offline
Points: 1085
I used to mount a scope and level the reticle by continually shouldering it, rotating the scope just a little, shouldering it, rotating it back and forth and then locking it down.  About 1/2 the time it seemed I would get to the range and set them in the bags and have the frustration of feeling that it was off level. 
 
I tried several leveling devices including the level-level-level.  A bore sighter does not work to level the reticle either.  Now I sight in on a 4' level 25 yards out the door on a fence while the rifle is shown to be uncanted with the EXD device.
 
Now when I set down to shoot at the bench and level the anti cant device the crosshairs appear perfect everytime.  Maybe it's all in my head anyway Loco.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/13/2009 at 20:12
John Barsness View Drop Down
Optics Optimist
Optics Optimist


Joined: January/27/2009
Status: Offline
Points: 785

Yeah, it can drive you nuts!

I have used various tools designed to level scopes, but generally I end up holding the rifle out in front of me a foot or two, with the scope set on its lowest magnification, then looking at the vertical part of the reticle to see if it is centered on the rear of the bolt. Unless there is something screwy with the mount (which can happen) then this seems to work as well as any other method. You can even make a mark on the center of the cocking piece to help lining everything up.

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/13/2009 at 22:08
RONK View Drop Down
Optics Master Extraordinaire
Optics Master Extraordinaire
Avatar

Joined: April/05/2007
Location: United States
Status: Offline
Points: 3199

 I've always thought that it would help a lot if scope manufactureres would mark a scribe line along the length of the tube at Bottom Dead Center, and make a small tick mark on the front or rear face of the bottom ring saddle to correspond with that line. You'd still have an occasional problem with bad receivers etc., but it would be a good starting point in leveling things up.

As it is, I found that holding the rifle out front and lining up the bottom part of the verticle reticle to the cocking piece or hammer works about as well as anything, as Mr. Barsness explained. For some reason, that's where  I'm always looking when trying to decide if it's level to the rifle. It just seems kind of a natural tendency for the eye to follow the reticle downward through the rifle as a sort of plumb bob when trying to make that determination.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 03:53
8shots View Drop Down
Optics Jedi Knight
Optics Jedi Knight
Avatar
Lord Of The Flies

Joined: March/14/2007
Location: South Africa
Status: Offline
Points: 5754
This topic has been discussed in detail on this nforum some time ago. Do a search.
The long and short of it is that if you have a canted reticule and you are going to dial elevation (or windage), the adjustment will run and the same angle that your reticule is canted. That stands to reason.
If you are going for Kentucky windage then a canted retcule does not matter, as long as you hold the center point directly above, below or to the side of where you are aiming off. In other words the cross may as well just be a dot as in an illuminated reticule.
If you cant your rifle, then the rifle will be dead on at the distance you zeroed it. The worse the cant and the further out you shoot, the more gravity will effect the arc of the bullet and cause the bullet to move away from your point of aim.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 07:57
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087

Getting the scope on straight is easy, it is getting the gun straight thats hard. This sound like its backwards, but its the real process that takes place. Each time the weapon is shouldered, it will be done at a different cant. Prone, causes a different cant than sitting, even standing -- a quick action shot has a different cant than holding the rifle in long range silhoutte shooting, skeet has a different cant than trap guns. Cant is more of problem for folks who shoot bench in really tight bean bags (or what ever set up) than action shooting sports. Hunting is the least affected. Some of the new electronic devices for cant are accurate enough to show offset between shots, but bubble levels are dubious at least for me.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 08:32
RifleDude View Drop Down
MODERATOR
MODERATOR
Avatar

Joined: October/13/2006
Location: Texas
Status: Offline
Points: 14313
I agree with Dale; the rifle is the hard thing to level.  It's quite often hard to get a reference plane among all the curved surfaces to use to square it up vertically.  I usually just put the rifle in a cleaning cradle I bought from Sinclair, sitting on a flat surface, then level the rifle as best I can with a small bubble level placed on a flat spot somewhere on the receiver, bold shroud, tang, etc.  If there are no flat spots somewhere on the receiver, I'll use a piece of flat stock secured to the top of the mount bases to set the bubble level on, if there's enough of the base protruding beyond the rings to do so.  I level the scope usually by hanging a string with a weight on the end (plumb bob) from a door frame and align the vertical post of the reticle with the string, careful not to move the leveled rifle in the process.  I do this in concert with the simple, plastic Segway reticle leveler.  Then, I don't worry about it anymore.  If the reticle is very slightly off level, it won't make much, if any difference in the field.
 
You'd be surprised how often the W/E turrets aren't square with the reticle, even on high-end scopes.  So, I totally disregard the position of the turrets, and you aren't aiming with them anyway.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 08:49
sakomato View Drop Down
Optics Master
Optics Master
Avatar

Joined: February/28/2008
Location: Houston
Status: Offline
Points: 1085
Originally posted by 8shots 8shots wrote:

If you are going for Kentucky windage then a canted retcule does not matter, as long as you hold the center point directly above, below or to the side of where you are aiming off. In other words the cross may as well just be a dot as in an illuminated reticule.
 
Hey 8shots, reticle cant can matter in Kentucky windage also, if you do what comes natural and line up your wanted point of impact along the vertical crosshair.  Then the crosshair would be up along the slanted verticle reticle and off to the side.
 
RD, you really need to get one of those EXD thingies
 
 
all the other levels will then be in your storage drawer.  IMO you can't get any less canted than drawing a straight line through the center of the bore and the center of the scope and then making sure that line is perfectly verticle.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 09:31
RifleDude View Drop Down
MODERATOR
MODERATOR
Avatar

Joined: October/13/2006
Location: Texas
Status: Offline
Points: 14313
You're right, Sako!  That is a great tool; I can tell just by looking at it.  I've seen them in the Brownells catalog, but I never ordered one; I don't know why.  You've now inspired me to get one, now that I have a good close-up look at it; in fact, I believe I'll order one today!!!Big Grin
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 16:40
RONK View Drop Down
Optics Master Extraordinaire
Optics Master Extraordinaire
Avatar

Joined: April/05/2007
Location: United States
Status: Offline
Points: 3199
 We use a tool something like that to lay out connection plate locations at various angles on pipe columns in our structural steel shop. The bubble is mounted in a marked compass 'turret' that can be set to the angle you want, up to 90 gegrees each side of vertical. When the bubble is centered, you release a spring-loaded punch that marks the column anywhere around its perimeter.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 19:52
jetwrnch View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: July/03/2006
Location: Knoxville, TN
Status: Offline
Points: 294
The real problem is round scope tubes! Square tubes with squared reticles = no problem.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 19:54
John Barsness View Drop Down
Optics Optimist
Optics Optimist


Joined: January/27/2009
Status: Offline
Points: 785
Wouldn't round reticles solve the problem too? Then we couldn't tilt 'em!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 21:05
sakomato View Drop Down
Optics Master
Optics Master
Avatar

Joined: February/28/2008
Location: Houston
Status: Offline
Points: 1085
Originally posted by jetwrnch jetwrnch wrote:

The real problem is round scope tubes! Square tubes with squared reticles = no problem.
 
The EXD kinda takes care of that with the v-yoke design
 
 
It seems to be well constructed and the horizontal bar was right on when I checked it with a 24" level
 
 
Originally posted by John Barsness John Barsness wrote:

Wouldn't round reticles solve the problem too? Then we couldn't tilt 'em!
 
Great idea, JB!!  A series of concentric circles!!  Thinking
 
Would be great for ranging and leading on a running shot!!  Sharp Shooter
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 21:16
Rancid Coolaid View Drop Down
Optics Jedi Master
Optics Jedi Master
Avatar

Joined: January/19/2005
Location: United States
Status: Offline
Points: 7698
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 21:21
greywolf View Drop Down
Optics Journeyman
Optics Journeyman
Avatar

Joined: April/25/2005
Status: Offline
Points: 310
I ordered one of the EXD devices yesterday and should get it next week - thanks for letting me know about it!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/14/2009 at 21:23
sakomato View Drop Down
Optics Master
Optics Master
Avatar

Joined: February/28/2008
Location: Houston
Status: Offline
Points: 1085
Laugh Above 
 
Can I use that!!
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Similar Threads: "physics of level scope reticles"
Subject Author Forum Replies Last Post
Level Level Level accurate enough?? jvr Rifle Scopes 4
Help ... Level rifle, scope and reticle bachekermooni Rifle Scopes 8
Scope reticle not level with turrets? DrBackJack Rifle Scopes 28
Entry Level FFP Reticle Scope Idaho Scot Varmint Scopes 4
Entry Level FFP Reticle Scope Idaho Scot Rifle Scopes 5
Scope reticle leveling / rifle cant Charlie-bolted Rifle Scopes 23
Reticle leveling video cheaptrick Shooting 12
Entry level spotting scope bugsNbows Optics For Sale 0
Ranging Reticle on a cranking scope, Why? sakomato Rifle Scopes 8
Easy way to level reticle Chris Farris Rifle Scopes 3 10/24/2004 1:33:53 PM


This page was generated in 0.219 seconds.