#2154555 - 04/17/08 12:34 PM
Level Question
|
Cheesy
Campfire Regular
Registered: 01/14/04
Posts: 880
Loc: SW Missouri
|
Offline
|
|
Hey guys, I don't venture into this forum much, but thought you all might enlighten me. One of the electricians that works for me is reading a book dealing with 'accurate shooting'. I can't recall the name of the book or author, will post that tomorrow if need be.
In it, the author is shooting with open sights. His front sight consists of an “H”, with the front aperature mounted in the top of the “H”. The author has a bubble level mounted in the top of the “H” directly below the aperature. He goes on to say that by having it at the top of the “H” it gives a more precise reading than having it at the bottom of the “H” (down by the barrel). The question is ‘why’? The sides of the “H” are parallel, no matter how much you cant the rifle, the bubble level is still going to be at the same angle relative to straight up and down, no matter whether the level is at the top or the bottom of the "H". Yes, the bubble will be a further horizontal distance from its origin, but no matter how much you cant the rifle, the level will always be at the same angle, no matter if it is high or low, correct?
Fill me in on this one, so I can look smart.  If I can get 1" groups, thats good enough for me, this digs a bit deeper than my needs.
|
|
Top
|
|
|
|
|
#2157403 - 04/19/08 07:36 AM
Re: Level Question
[Re: Cheesy]
|
Tod
Campfire Tracker
Registered: 12/17/06
Posts: 5036
Loc: Helena MT
|
|
Offline
|
|
The farther the bubble is from centerline, the more a deviation is amplified. It's the same theory as sight radius.
_________________________
Giving money and power to government is like giving whiskey and car keys to teenage boys.
-- P. J. O'Rourke
|
|
Top
|
|
|
|
|
#2160491 - 04/21/08 07:02 AM
Re: Level Question
[Re: Tod]
|
Cheesy
Campfire Regular
Registered: 01/14/04
Posts: 880
Loc: SW Missouri
|
|
Offline
|
|
I don't think it is the same theory as sight radius though.
Example of the front and rear sight on a pistol compared to the front and rear sight on a long barreled rifle, its easier to see a slight misalignment when you're 20"+ between sights than when you're only 5". MIsalignment might not be the right word there, but what appears to the pistol shooter as the sights lining up could really be off a few degrees, causing his shots to go wide, where the longer distance between a rifles sights is a more sure way of making sure all 3 points are in a line (rear sight, front sight, target).
tan*=opp/adj For a given angle of cant (*) as you increase the adjacent leg (the distance from barrel center to bubble level) you also increase the opposite leg (horizontal distance from sight in vertical position to canted position) I would understand this if you had a device that was measuring the opposite leg, but a bubble is just measuring the angle, not distances (unless I don't understand a shooting level, never seen one, never used one) So no matter whether the level was a quarter inch from center of the barrel, or a mile from the barrel, its still going to show the bubble as being in the same place in the level.
Maybe I'm all washed up, and making it more difficult than need be. I am a mechanical engineer by schooling, and ran this through 3 other engineers, as well as a couple of fairly competent shooters, and none of us could make sense of it. The only answers we have came up with from others wouldn't matter on a level, only on something that would measure horizontal distances, in effect, something that could be measured with a tape measure.
|
|
Top
|
|
|
|
|
#2161301 - 04/21/08 02:37 PM
Re: Level Question
[Re: Cheesy]
|
Tod
Campfire Tracker
Registered: 12/17/06
Posts: 5036
Loc: Helena MT
|
|
Offline
|
|
Cheesy, I think you're right. I shouldn't post before coffee.
_________________________
Giving money and power to government is like giving whiskey and car keys to teenage boys.
-- P. J. O'Rourke
|
|
Top
|
|
|
|
|
#2169882 - 04/26/08 01:15 AM
Re: Level Question
[Re: Tod]
|
Middlefork_Miner
Campfire Regular
Registered: 06/16/07
Posts: 886
Loc: Way past prime time
|
|
Offline
|
|
The farther the bubble is from centerline, the more a deviation is amplified. It's the same theory as sight radius.
_________________________
Dogs...They just don't live long enough...gonna miss you Bear...R.I.P. my friend.
|
|
Top
|
|
|
|
|
#2169885 - 04/26/08 01:27 AM
Re: Level Question
[Re: Middlefork_Miner]
|
Middlefork_Miner
Campfire Regular
Registered: 06/16/07
Posts: 886
Loc: Way past prime time
|
|
Offline
|
|
The further the bubble is from centerline, The more accuratly you'll be able to judge...sure...it'll still be at the same angle but it will be easier for the eye to pick up
_________________________
Dogs...They just don't live long enough...gonna miss you Bear...R.I.P. my friend.
|
|
Top
|
|
|
|
|
#2173111 - 04/28/08 09:25 AM
Re: Level Question
[Re: Middlefork_Miner]
|
Cheesy
Campfire Regular
Registered: 01/14/04
Posts: 880
Loc: SW Missouri
|
|
Offline
|
|
This has been bothering me for the last several days, so I finally took the time and drew a quick and dirty of it up in CAD. I've attached my drawing as a jpg. It shows a barrel (blue), with a level mounted on top of it (red), in the level is the bubble (green), then I've drawn in another level a further distance away with the same blue level. Everything about the levels is the same as far as sizes, radii, etc. On top of that I drew in a little red front site just for the heck of it. I then copied these and moved them to the side with rotations of 5, 10, 15, and 20 degrees. I then drew in a line representing the highest point on the level which is where the bubble is going to go (represented by a green line in the picture). No matter how much you tilt the setup, the bubble is still going to go to the same spot in the level, appearing the same to the shooter.
I initially had myself convinced that I had been wrong this whole time, that the bubble is going to try and go to the original centerline, but taht doesn't make sense as it is just going to go to the high spot of the level (represented by the horizontal green line).
I'm pretty convinced I am right on this, so if there is a flaw in my drawing or logic, please tell me so and why. I'm not keeping this up to be difficult, just trying to understand and make sense of it. If somebody wants the original autocad drawing to play with and add some discriptors or whatever, let me know, I'd be happy to send it.
Attachments
9867-leveldrawing.JPG (41 downloads)
|
|
Top
|
|
|
|
|
#2174583 - 04/29/08 05:46 AM
Re: Level Question
[Re: Cheesy]
|
ChrisF
Member
Registered: 07/13/03
Posts: 154
|
|
Offline
|
|
Cheesy,
I agree with your analysis. If you draw a plumb line down from the level, in each case the angle to plumb remains the same. The bubble move the same amount regardless because the angles to plumb are the same. What the "shooter" might be referring to is if he uses the higher mounted level as a gross visual point of referrence in addition to the bubble's finer reference. A higher mounted level would show more displacement "visually" than would a lower mounted level (ignoring the bubble of course). One "possible benefit might be getting him into position more quickly with the gross visual of the high-mounted-level, then fine-tuning done with the bubble. I have a strong suspicion on who the shooter in question is.
Edited by ChrisF (04/29/08 05:51 AM)
|
|
Top
|
|
|
|
Moderator: RickBin, SYSOP
|
|
|
|
|
1
|
2
|
3
|
4
|
|
5
|
6
|
7
|
8
|
9
|
10
|
11
|
|
12
|
13
|
14
|
15
|
16
|
17
|
18
|
|
19
|
20
|
21
|
22
|
23
|
24
|
25
|
|
26
|
27
|
28
|
29
|
30
|
31
|
|
|
18914 Members
65 Forums
197684 Topics
2433783 Posts
Max Online: 1366 @ 08/07/07 07:51 PM
|
|
|
