Bubble level for rifle

[Dave King]

This chart is for ALL degrees, from 1 to 90. Is someone missing that point??

I'll bold the 6 degree values.

<UL TYPE=SQUARE>

First column is cant error (horizontal displacement) in inches.

Second column is inclined fire type error for the same degree of inclination in inches.

Third column is the degree from horizontal (inclined) or vertical (cant)

Cant Incl Angle in degrees
1.36 0.01 1
2.72 0.04 2
4.08 0.10 3
5.44 0.19 4
6.79 0.29 5

8.15 0.42 6

9.50 0.58 7
10.8 0.75 8
12.2 0.96 9
13.5 1.18 10
14.8 1.43 11
16.2 1.70 12
17.5 1.99 13
18.8 2.31 14
20.1 2.65 15
21.4 3.02 16
22.8 3.40 17
24.1 3.81 18
25.3 4.24 19
26.6 4.70 20
27.9 5.18 21
29.2 5.67 22
30.4 6.20 23
31.7 6.74 24
32.9 7.30 25
34.1 7.89 26
35.4 8.50 27
36.6 9.13 28
37.8 9.77 29
39.0 10.4 30
40.1 11.1 31
41.3 11.8 32
42.4 12.5 33
43.6 13.3 34
44.7 14.1 35
45.8 14.8 36
46.9 15.7 37
48.0 16.5 38
49.0 17.3 39
50.1 18.2 40
51.1 19.1 41
52.1 20.0 42
53.1 20.9 43
54.1 21.8 44
55.1 22.8 45
56.1 23.8 46
57.0 24.8 47
57.9 25.8 48
58.8 26.8 49
59.7 27.8 50
60.6 28.9 51
61.4 29.9 52
62.2 31.0 53
63.1 32.1 54
63.8 33.2 55
64.6 34.3 56
65.4 35.5 57
66.1 36.6 58
66.8 37.8 59
67.5 39.0 60
68.2 40.1 61
68.8 41.3 62
69.4 42.5 63
70.1 43.8 64
70.6 45.0 65
71.2 46.2 66
71.7 47.5 67
72.3 48.7 68
72.8 50.0 69
73.2 51.3 70
73.7 52.6 71
74.1 53.8 72
74.5 55.1 73
74.9 56.5 74
75.3 57.8 75
75.6 59.1 76
76.0 60.4 77
76.2 61.7 78
76.5 63.1 79
76.8 64.4 80
77.0 65.7 81
77.2 67.1 82
77.4 68.4 83
77.5 69.8 84
77.7 71.2 85
77.8 72.5 86
77.8 73.9 87
77.9 75.2 88
77.9 76.6 89
78.0 78.0 90

[/list]

What I'm saying, is that based on what I've tested and what I believe the error induced by 6 degrees of cant is ~8.15 inches of horizontal displacement at about 500 yards with a 308 Win.

The error induced by 90 degrees of cant is about 78 inches of horizontal displacement at 500 yards.

One degree of cant produces ~ 1.36 inches of horizontal displacement at 500 yards (a value that is probably lost in the noise of other errors).

Clearer now??

[ 03-05-2004: Message edited by: Dave King ]

 

[Dave King]

Brent

I downloaded the RSI Labs demo.

I used 2650 FPS, BC .473, STP (-0- alt, 59 degrees, etc)

Unchecked Calc Max Point Blank Range.

Set Impact range at 500 yards.

Set sight height to 1.75 inches.

RSI shows ME a 7.88 inch deflection with a cant of 6 degrees induced.

Total Drop for this test is 80.66 inches at 500 yards, close to my sample of 78 inches.

90 degrees of cant shows 78.65 inches of deflection. I don't understand the disparity between the 80.66 and the 78.65, I believe they should be equal.

[ 03-05-2004: Message edited by: Dave King ]

 

[4mesh063]

No Dave, I am not for one second disputing the 78" elevation, I don't care if you make it 100 for ease of the math. The Exaggerated numbers I was talking about, are the 8" at 500. Impossible. Yes, under test conditions you can do that. While TRYING TO HOLD that far off level. I will repost your own photos, modified to show you the real results of being disoriented. You have plainly tried to snow someone by rotating the Elk. Well, I don't care if the elk stands upright on his back feet, If my crosshairs are level, I'll kill him in 1 shot. Now, If you put the elk back where he was and rotate the crosshairs like you should have in the first place, you would plainly see that there is no way on Gods green earth anyone could miss that. I would have to have had an auto accident and severe head trauma on my way to hunting camp.

Your own photo of the elk shows them walking down a hill as you astutely pointed out to me. Yes, I noticed it was downhill , even though it was so slight. THAT IS LESS THAN a 6 degree angle they are walking down and YOU are telling me that there is a person who owns guns and shoots at game at ranges of 500 yards or more, who cannot distinguish DOUBLE THAT. PLUS OR MINUS. Someone out there looks at that picture in the wild and cannot tell if the elk are walking downhill, uphill, or on the level because they are disoriented? Please take thier gun away!

It is becoming obvoius that evolution of the elk and mule deer is going to be accelerated drastically.

I predict that in the states where You and Ric hunt, there will be no living game with 4 legs remaining as all of them will have had thier front legs shot off. Elk and Mulies are going to be biped mammals that walk upright by the year 2020!

Rotate the elk on a 90 and you'll see what they will look like in a few years!

I'll post the photos later.

Brent:

I clearly said that IF you have a canted situation present and you have not noticed it. You should stay away from guns. If you cannot get your scope level within 6 degrees, stay away from guns! If you vary from shot to shot by 6 degrees of hold, stay away from guns.

Furthermore, If you hunt game at long range and you have no idea of where your gun shoots at long range, you also have not fired at long range, AND you have a 100 yard zero on your gun, AND you are going to attempt a FIRST SHOT KILL on game at long range by dialing an elevation on an untested rifle, you are an idiot and should not have a gun.

You have already plainly stated (in the above referenced thread) that you experienced this phenomenon while practicing with your hunting rifle. Thank you. You also have taken steps to eliminate it by fixing the out of level optics OR by adjusting for the error which you know to exist. Again, fine. PROBLEM SOLVED. You cannot possibly tell me that from that point forward, you have ever held your gun far enough off level to ever see it again! No way!

The errors you are looking for is derived from the difference between two situations. I will describe them clearly.

Practice:
I hold my gun and shoot at targets till I can hit what I am aiming at.

Real Life Hunting:
I hold my gun so differently from my practice that there is an insane variation in what I perceive as level because I happen to be outside and there could be hills there. I no longer can distinguish uphill or downhill within a mile from level because I am looking through the same scope that I had no trouble with the other day.

We are talking about crosshairs being level, not elk being more difficult to shoot and points of impact changing when they are on a hill.

Dave, I do not dispute the numbers you have for a 6 degree cant causing an 8" error at 500. Roughly. I have not checked them nor am I going to. I'll accept that, even though everyone else seems to think that it's significantly less. It matters not. If you are disoriented to the extent that you do not notice 1 degree of gun cant, stay away from drugs. They are bad for ya.

 

[4mesh063]

Dave,
The disparity is the sight height not included in the one figure.

 

[Brent]

Dave,
I'll have to run it that way and look, I just ran the 3100 fps 210gr BC .640 at standard sea level conditions.

I'd like to post all the windows I saved (27 of them) but there's 2.0mb in all of them. About 75kb per screen shot.

I'll post some. I did 1, 2, 4 and 6 deg at 100, 500 and 1000 yards. One screen shot with deflection in MOA, and another in inches.


500 yards, 1 degree cant
*

***

500 yards, 2 degree cant
*

***

500 yards, 4 degree cant
*

***

500 yards, 6 degree cant
*

***

1000 yards, 1 degree cant
*

***

1000 yards, 2 degree cant
*

***

1000 yards, 4 degree cant
*

***

1000 yards, 6 degree cant
*

***

Should be plenty enough to evaluate.

 

[Dave King]

4mesh063

I already told you I rotated that elk 6 degrees, here's the entire picture rotated to a similar 6 degrees.

I believe the disparity, what you elect not to see or understand is that folks (not the almighty "target weenies") are cursed by nature and the mechanisms of vision to try to orient the planet and objects in it into a "normal" condition. Concentrate on the elk (or whatever critter/target) and shooters will tend to orient the cross hairs to the target.

If there were no place/need for these devices there'd be a lot less on the market. There would also be far fewer articles, studies and research into the subject of cant induced error if we all were blessed with a "gravity memory" like yours. Point of fact is that cant error(s) does exist and one needs to be aware of it regardless of what you may think.

No one is forcing you to buy one of these levels or to even think about us poor slobs that have ****ed away our hard earned dollars on such a UBF (U been f***ked) item.


Brent


Okay, I created a JPG from the one I had.

6 degrees of cant.

[ 03-05-2004: Message edited by: Dave King ]

 

[4mesh063]

How many times do I have to say it to you Dave?

You act as if I'm the one who is dense!

ROTATE THE CROSSHAIRS, NOT THE ELK!

I refered to the disparity in response to your question of why the drop number does not coincide with the error of impact on a 90 deg shot when the gun is laying on it's right. The answer is because the drop figure has the scope sight height accounted for in level fire, but when it is fired with the gun on a 90 deg cant to the right, the error is reduced by the fact that the barrel is now on the LEFT side of the sight line by 1.750" in your example. This is also necessary to account for, in all the angles of rotation &gt;0 - =90. These would be 2 part figures, found by using your Trig functions in relation to the 1.75" and the angle.

 

[4mesh063]

I have a Bald Eagle Rest for shooting off of. I just checked it so that people out there can relate to the angles we are talking about.

If I adjust the feet to the extremes in both directions, I have a GRAND TOTAL of 5.5 Degrees of adjustment on BOTH SIDES COMBINED. That's 2.75 degrees each way right or left. For anyone with a rest such as this, How many times have you set up your portable shooting bench, leveled it by eye making even the remotest effort to make it right, and then run out of adjustment on your shooting rest because you missed by a mile when setting up on uneven ground?

They also sold Pet Rocks Dave. How many of them did you buy because you had to have one?

[ 03-05-2004: Message edited by: 4mesh063 ]

 

[Brent]

Phil,
I really don't know if I misunderstand what you're saying reguarding the reticle of my dad's being off when the bubble inside it is level, or a couple other things you said reguarding my shooting it or maybe another rifle at LR, but I do know the crosshair was tipped over 4 degrees or so when the bubble inside it was level. I did not look at a plumb line down range, just the ground that is fairly level where the target stand was setting. Close enough for him and I to see the crosshairs were canted.

I've shot at LR with a target, frame or what have you not close to plumb and the ground isn't either. Looking into a dirt backstop with no frame of referance either, I gurantee that I could be off 1 or 2 degrees, maybe more. Shot to shot? No, but when I start shooting and decide how I will hold on the target, which becomes the referance, I may very well indeed be off from the last time I shot there if the frame was tilted, target or what have you, than the time before. IF YOU USE A LEVEL ON THE SCOPE WHILE SHOOTING, THIS IS A NON-ISSUE.

If I shot 1k BR, I would never need a level on my scope, but I would still have one. The sighters and target frame would be a referance that GAURANTEED a CONSISTANT hold EVERY shot, DAY TO DAY or what ever. THAT'S ALL THE LEVEL IS, THE PERFECT FRAME OF REFERANCE.

I have no intent on arguing the deflection numbers, or whether it is significant enough to use, whether you should be touching a rifle or not. I merely submit this for one to consider, and that's all I ever try to do, is consider what's presented. There is much BS on this board, and others too, that does me no good, I take the good and leave the bad and move on...

I hold my rifle level, I don't shoot with it canted, that's what the level is for. Dave may shoot 90 deg shots or what have you, but the main deal for me is to be consistant and focus on what I have has to be compensated for, namely wind.

I am removing the error associated with cant just because I can, just like I would anything I could, which contributes to consistant, precise shot placement.

Fact remains, it is an error, and it is significant at LR. Significant enough for one to account for? I guess it depends on the target size and a few more things the prudent would consider, to even say. If I shot 1k BR or Mosse at near 1k yards, I would.

I don't see the logic in arguing that I would be more accurate, or just as accurate without a level on my rig but, I do see the logic in the opposing arguement.

Unless an animal is directly facing me, or away, and gravity becomes CLEARLY visual through my scope, or I'm on flat ground shooting LR, I'll take the level.

 

[4mesh063]

Brent,

I have already said that YOU have taken steps for this not to be an issue. The people I am refering to are the ones who I'm being told exist, who need this device to distinguish level crosshairs from unlevel ones to such a degree that they make adjustments of 6 degrees either way depending upon the ground they stand on.

I have already conceded that I will give you an error of 1 degree from level as understandable. I have also said that no living person could make an error much more than this regardless of the situation they are in. The errors come not from how far a gun can be tilted in a rest, but, how differently they hold thier hunting rifle from situation to situation. At 500 yards, I will give you that there is 1.5" roughly of error that could be produced in a WORST CASE scenario. I have done this sort of shooting off a bipod for years before I ever competed and used to go shoot at steel from all sorts of locations, differing ranges, varied terrain, and all in an area where there is absolutely no reference whatsoever. The woodsline that I think you have the photos of, is a downhill slant to the left very slightly. It has NEVER caused me to hold my gun off level. Nor would it you or anyone else.

I cannot understand how someone thinks that I am claiming to be better at holding a gun than someone else when I clearly state that I feel that this is impossible for ANYONE to do.

You, I know do not make stupid shots at game and you practice regularly in order to make sure of it. Firing till sore for days is a good example. Many here do not. Then, they advocate a device which helps you to improve your point of aim by 1/2 of a click, while using a Mil-dot. Sound more insignificant yet?

Please don't confuse WANT with NEED. I have no problem with want. A person from Hawaii who WANTS heated seats is understandable. If they say they NEED them, they need help.

I don't want a beer. I NEED one.

 

[Dave King]

4mesh063

The crosshairs in Picture #2 ARE rotated, 6 degrees. That's the point, you can't see it because the elk is also rotated 6 degree (by nature, not by me). I simply aligned the crosshairs to the rest of the world as it was visually presented, there's a term for this, it's called cant.

And with that I'm done with you. Initially I thought that you were just ignorant and you could eventually figure this out but it's apparent that you are far to stupid to see the problem.

 

[Boyd Heaton]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>I believe the disparity, what you elect not to see or understand is that folks (not the almighty "target weenies") are cursed by nature <HR></BLOCKQUOTE>Whoa there Dave.That blanket statement was a touch uncalled for don't you think????I'm not sure how I ever got by without having one of those cute little bubble thingies on my gun.I have seen the light

 

[4mesh063]

So, I'm the one who is "Stupid". Too stupid to understand?

Well, Dave, MR almighty example of higher intelligence. It would appear that when you tilt your scope, the ENTIRE WORLD turns with it! Immagine how the mountain rolls to the left at the same time your scope does! That's amazing. When I aim, I can turn my gun to the side and the world stays upright! You must have higher connections than I have. I did notice a shift in the earth the other day. Were you shooting?

THIS photo is the REAL image we would see if we were hunting under the influence. The world allways stays put here Dave. It's the gun that rotates. At some point you have to look at at least some part of the image to verify that it is really not upside down.

I have "neglected" to see the majority of this as anyone with 2 brain cells would also see. This entire discussion is about the possibility of this happening by ACCIDENT and that is simply not possible.

YOU, my man are a salesperson. Do you get a kickback on these things?

I now finally understand how this is possible and I admit my mistake. I can plainly see that YOU would not see this because YOU hunt with your head up your ***! Now, I agree, this is possible.

 

[4mesh063]

By the way, YOU are the one who knows everything about canted shooting and does NOT understand that when the gun is on its SIDE, the barrel is BESIDE the scope.