Okay, I think I understand what you are saying, BUT, regardless of sight offset, once the system is set up I would think you still need to keep it as close to level as possible to remove any possibility of error. When I have more time I will re-read your post and try to understad it better, right now the boss is giving me the evil eye! (And I am self employed!)
microlevel
- Thread starter thedecline
- Start date
- Location
- Somewhere on the Hudson Bay Coast
That would be the bubble level located on top of the angle/slope indicator . . . two birds with one stone.
I've got mine, and find it useful enough. Your point about the scale of the diagram is well taken, but the text seems to get the point across that's why I posted it.
here is a guy that went out and did an experiment on canting it is a great observation.
The effects of side to side cant - field test/pics
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2373787&page=1
Bryan Litz commented on the results
Thanks for doing this test and sharing the results.
I'm a HUGE advocate of using levels for long range shooting. If you're shooting past 300 yards a level is indispensable.
It's always gratifying to see when a ballistics model prediction matches what happened in a field test. I consider the prediction of 9" to *match* the result of 10.3R and 8.1L. Why it was more in one direction than the other, and why the groups were bigger are good questions, but I'd like to focus on the ballistics for now.
The models (JBM) prediction was accurate at 600 yards, so we should be confident it's solving the problem correctly and will provide accurate predictions at other ranges as well. JBM predicts around 30" of horizontal displacement for a similar trajectory with 5 degrees cant at 1000 yards, which is a far more dramatic displacement than the 9" at 600. Granted you're unlikely to have 5 degrees of cant in any scenario where you're trying for zero, but is it possible to have 2.5 degrees of cant with the unaided eye? That corresponds to a 15" miss.
With the use of a level, I estimate you can resolve within +/- 0.5 degrees pretty easily, which narrows your 'cant' miss distance down to less than 3" at 1000 yards, regardless of the terrain, or if you have any good vertical or horizontal reference lines in your FOV. Why not use the aid? It's not heavy or intrusive. You can ignore it on close shots where it's not as critical.
For those who were interested about the math of determining cant, it's pretty easy. You essentially take the total drop at the range of interest, and multiply by the sin of the cant angle. For example, if the total drop from the bore line is 300" (typical 1000 yard drop), and you have a 5 degree cant, the horizontal displacement will be 300*sin(5) = 26". If the cant angle is 1 degree, the displacement is 300*sin(1) = 5". This leads to a rule of thum
for every 1 degree of cant, you suffer about 5" of horizontal displacement at 1000 yards (more or less depending on how flat the trajectory is).
It's pretty easy to visualize where the error comes from if you take it to the extreme. For example, if you shot with a 45 degree cant, and you had 30 MOA of elevation dialed on, then you can expect that a great deal of that 30 MOA of sight adjustment will be horizontal. If the scope is canted 90 degrees (laying on it's side), then all 30 MOA is horizontal. The case of a slight cant is the same effect, but to such a small degree that it's harder to visualize. When you have 30 MOA dialed on, and the scope is tilted slightly to the size, a small component of that 30 MOA 'bleeds into' the horizontal plane.
Imagine if you were using a reticle hold over, and there was a big cant. Using a reticle hold-over by putting a mil-dot (or some other reticle feature) directly on the target, the actual cross-hair is not directly above the target. The bullet will fall from the center of the cross-hair (because that's how gravity works) and will strike below the cross-hair where, in the case of excessive cant, the target isn't.
Once again brasscow, thanks for the effort.
-Bryan
The effects of side to side cant - field test/pics
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2373787&page=1
Bryan Litz commented on the results
Thanks for doing this test and sharing the results.
I'm a HUGE advocate of using levels for long range shooting. If you're shooting past 300 yards a level is indispensable.
It's always gratifying to see when a ballistics model prediction matches what happened in a field test. I consider the prediction of 9" to *match* the result of 10.3R and 8.1L. Why it was more in one direction than the other, and why the groups were bigger are good questions, but I'd like to focus on the ballistics for now.
The models (JBM) prediction was accurate at 600 yards, so we should be confident it's solving the problem correctly and will provide accurate predictions at other ranges as well. JBM predicts around 30" of horizontal displacement for a similar trajectory with 5 degrees cant at 1000 yards, which is a far more dramatic displacement than the 9" at 600. Granted you're unlikely to have 5 degrees of cant in any scenario where you're trying for zero, but is it possible to have 2.5 degrees of cant with the unaided eye? That corresponds to a 15" miss.
With the use of a level, I estimate you can resolve within +/- 0.5 degrees pretty easily, which narrows your 'cant' miss distance down to less than 3" at 1000 yards, regardless of the terrain, or if you have any good vertical or horizontal reference lines in your FOV. Why not use the aid? It's not heavy or intrusive. You can ignore it on close shots where it's not as critical.
For those who were interested about the math of determining cant, it's pretty easy. You essentially take the total drop at the range of interest, and multiply by the sin of the cant angle. For example, if the total drop from the bore line is 300" (typical 1000 yard drop), and you have a 5 degree cant, the horizontal displacement will be 300*sin(5) = 26". If the cant angle is 1 degree, the displacement is 300*sin(1) = 5". This leads to a rule of thum
for every 1 degree of cant, you suffer about 5" of horizontal displacement at 1000 yards (more or less depending on how flat the trajectory is).It's pretty easy to visualize where the error comes from if you take it to the extreme. For example, if you shot with a 45 degree cant, and you had 30 MOA of elevation dialed on, then you can expect that a great deal of that 30 MOA of sight adjustment will be horizontal. If the scope is canted 90 degrees (laying on it's side), then all 30 MOA is horizontal. The case of a slight cant is the same effect, but to such a small degree that it's harder to visualize. When you have 30 MOA dialed on, and the scope is tilted slightly to the size, a small component of that 30 MOA 'bleeds into' the horizontal plane.
Imagine if you were using a reticle hold over, and there was a big cant. Using a reticle hold-over by putting a mil-dot (or some other reticle feature) directly on the target, the actual cross-hair is not directly above the target. The bullet will fall from the center of the cross-hair (because that's how gravity works) and will strike below the cross-hair where, in the case of excessive cant, the target isn't.
Once again brasscow, thanks for the effort.
-Bryan
Does anyone have an opinion on the scoplevel? I'm thinking of ordering a few to try out.
Of the reviews I've read online, some complain that it's plastic (which is good to me, since there's less chance of scratching the scope tube) and care must be taken when tightening the screws, but otherwise the reviews are quite favorable.
Of the reviews I've read online, some complain that it's plastic (which is good to me, since there's less chance of scratching the scope tube) and care must be taken when tightening the screws, but otherwise the reviews are quite favorable.
rnbra-shooter
CGN Ultra frequent flyer
- Location
- New Brunswick
@agent_mango I have a "ScopLevel" which I think is the same thing you are talking about. It is plastic and it flips up and down. It isn't a $200 chunk of milspec black aluminum with eight recessed hex head screws to hold it in place, but I think that for what it is it is well done. I am happy with it.
This one from US Optics is great too...
You can see it without taking your eyes off the scope (if you shoot with both eyes open) and it folds away when you don't need it.
http://www.usoptics.com/accD.php?recordID=BBL-350
You can see it without taking your eyes off the scope (if you shoot with both eyes open) and it folds away when you don't need it.
http://www.usoptics.com/accD.php?recordID=BBL-350
know any dealers for these?
- Location
- Halifax, NS
The problem:
The solution:
The challenge:
Horus Vision won't ship to Canada, so some skullduggery is required to get one.
FALSE (...or in my case at least)
I bought mine from their website directly. As easy as buying speakers from ebay.
On a side note, buy the scope mounted one. The rail mounted one I have isnt level when the bubble is lined up. No big deal, still a great, cost efective option ($70 vs $200).
It's the best pic I have on hand.
here is a guy that went out and did an experiment on canting it is a great observation.
The effects of side to side cant - field test/pics
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2373787&page=1
Bryan Litz commented on the results
Thanks for doing this test and sharing the results.
I'm a HUGE advocate of using levels for long range shooting. If you're shooting past 300 yards a level is indispensable.
It's always gratifying to see when a ballistics model prediction matches what happened in a field test. I consider the prediction of 9" to *match* the result of 10.3R and 8.1L. Why it was more in one direction than the other, and why the groups were bigger are good questions, but I'd like to focus on the ballistics for now.
The models (JBM) prediction was accurate at 600 yards, so we should be confident it's solving the problem correctly and will provide accurate predictions at other ranges as well. JBM predicts around 30" of horizontal displacement for a similar trajectory with 5 degrees cant at 1000 yards, which is a far more dramatic displacement than the 9" at 600. Granted you're unlikely to have 5 degrees of cant in any scenario where you're trying for zero, but is it possible to have 2.5 degrees of cant with the unaided eye? That corresponds to a 15" miss.
With the use of a level, I estimate you can resolve within +/- 0.5 degrees pretty easily, which narrows your 'cant' miss distance down to less than 3" at 1000 yards, regardless of the terrain, or if you have any good vertical or horizontal reference lines in your FOV. Why not use the aid? It's not heavy or intrusive. You can ignore it on close shots where it's not as critical.
For those who were interested about the math of determining cant, it's pretty easy. You essentially take the total drop at the range of interest, and multiply by the sin of the cant angle. For example, if the total drop from the bore line is 300" (typical 1000 yard drop), and you have a 5 degree cant, the horizontal displacement will be 300*sin(5) = 26". If the cant angle is 1 degree, the displacement is 300*sin(1) = 5". This leads to a rule of thum
It's pretty easy to visualize where the error comes from if you take it to the extreme. For example, if you shot with a 45 degree cant, and you had 30 MOA of elevation dialed on, then you can expect that a great deal of that 30 MOA of sight adjustment will be horizontal. If the scope is canted 90 degrees (laying on it's side), then all 30 MOA is horizontal. The case of a slight cant is the same effect, but to such a small degree that it's harder to visualize. When you have 30 MOA dialed on, and the scope is tilted slightly to the size, a small component of that 30 MOA 'bleeds into' the horizontal plane.
Imagine if you were using a reticle hold over, and there was a big cant. Using a reticle hold-over by putting a mil-dot (or some other reticle feature) directly on the target, the actual cross-hair is not directly above the target. The bullet will fall from the center of the cross-hair (because that's how gravity works) and will strike below the cross-hair where, in the case of excessive cant, the target isn't.
Once again brasscow, thanks for the effort.
-Bryan
this ^^^^ the hide has all the info
here is a guy that went out and did an experiment on canting it is a great observation.
The effects of side to side cant - field test/pics
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2373787&page=1
Bryan Litz commented on the results
Thanks for doing this test and sharing the results.
I'm a HUGE advocate of using levels for long range shooting. If you're shooting past 300 yards a level is indispensable.
It's always gratifying to see when a ballistics model prediction matches what happened in a field test. I consider the prediction of 9" to *match* the result of 10.3R and 8.1L. Why it was more in one direction than the other, and why the groups were bigger are good questions, but I'd like to focus on the ballistics for now.
The models (JBM) prediction was accurate at 600 yards, so we should be confident it's solving the problem correctly and will provide accurate predictions at other ranges as well. JBM predicts around 30" of horizontal displacement for a similar trajectory with 5 degrees cant at 1000 yards, which is a far more dramatic displacement than the 9" at 600. Granted you're unlikely to have 5 degrees of cant in any scenario where you're trying for zero, but is it possible to have 2.5 degrees of cant with the unaided eye? That corresponds to a 15" miss.
With the use of a level, I estimate you can resolve within +/- 0.5 degrees pretty easily, which narrows your 'cant' miss distance down to less than 3" at 1000 yards, regardless of the terrain, or if you have any good vertical or horizontal reference lines in your FOV. Why not use the aid? It's not heavy or intrusive. You can ignore it on close shots where it's not as critical.
For those who were interested about the math of determining cant, it's pretty easy. You essentially take the total drop at the range of interest, and multiply by the sin of the cant angle. For example, if the total drop from the bore line is 300" (typical 1000 yard drop), and you have a 5 degree cant, the horizontal displacement will be 300*sin(5) = 26". If the cant angle is 1 degree, the displacement is 300*sin(1) = 5". This leads to a rule of thum
It's pretty easy to visualize where the error comes from if you take it to the extreme. For example, if you shot with a 45 degree cant, and you had 30 MOA of elevation dialed on, then you can expect that a great deal of that 30 MOA of sight adjustment will be horizontal. If the scope is canted 90 degrees (laying on it's side), then all 30 MOA is horizontal. The case of a slight cant is the same effect, but to such a small degree that it's harder to visualize. When you have 30 MOA dialed on, and the scope is tilted slightly to the size, a small component of that 30 MOA 'bleeds into' the horizontal plane.
Imagine if you were using a reticle hold over, and there was a big cant. Using a reticle hold-over by putting a mil-dot (or some other reticle feature) directly on the target, the actual cross-hair is not directly above the target. The bullet will fall from the center of the cross-hair (because that's how gravity works) and will strike below the cross-hair where, in the case of excessive cant, the target isn't.
Once again brasscow, thanks for the effort.
-Bryan
After reading that article I bought a vortex level for my Millett and I was impressed by how precise the level was and how it helped improve my ability to repeat shots. I don’t like to use the horizon or a target stand as a level because they are not always level, and just going from target to target I notice a difference now (regarding how level they actually are).
