oldspook
Super Contributor
Posts: 404 
ATN Products Owned: Smart HD Optics
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Post by oldspook on Mar 21, 2017 14:51:04 GMT -8
The default profile in the X-Sight II is:
G1 drag function
150 grain bullet
0.48 BC
1.5 inch sight height
2798.56 fps
99.52 yard zero
The default profile in the Android LRF app is not identical but it is close so I just made the adjustments necessary to ensure that both of the profiles were identical and then performed a simple exercise.
From my window I ranged a pole at 469 yards the inclination was -3 and let the app give me a solution. The solution was 37 up and we will ignore windage. At that range 37 1/4 MOA clicks equates to 45.406". I then fired up the X-Sight and took the same range. I got 470 yards and -1 inclination. The X-Sight SSS returned an up correction of 46.68". That's pretty good agreement for that range and a couple of degrees difference in inclination.
Now here is the bad news...
Using Applied Ballistics I set up an identical bullet profile. I set up the same firing solution and Applied Ballistics (what the pros use) gave me a come up of 9.4 MOA which agrees almost exactly with the ATN solutions. Then I enabled powder temperature compensation, Coriolis and Spindrift. The correct solution according to Applied Ballistics is up 14.5 MOA. So we are talking about an error of 5.5 MOA at 470 yards. That is 27 inches. That's two feet and three inches.
Can these issues be corrected for in your long range shooting? YES but it is important that you know that these LIMITATIONS exist. Your X-Sight/LRF combination will get you just close enough at 400 yards to cripple your target if you don't understand the limitations of the ballistics calculator you are getting from ATN.
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jdb
Contributor
Posts: 41
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Post by jdb on Mar 22, 2017 5:22:19 GMT -8
I don't know what temperature compensation you are using, but combined coriolis/spin drift shouldn't approach 5.5 MOA at 470 yards.
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Post by waltlongmire on Mar 22, 2017 11:08:00 GMT -8
The default profile in the X-Sight II is: G1 drag function 150 grain bullet 0.48 BC 1.5 inch sight height 2798.56 fps 99.52 yard zero The default profile in the Android LRF app is not identical but it is close so I just made the adjustments necessary to ensure that both of the profiles were identical and then performed a simple exercise. From my window I ranged a pole at 469 yards the inclination was -3 and let the app give me a solution. The solution was 37 up and we will ignore windage. At that range 37 1/4 MOA clicks equates to 45.406". I then fired up the X-Sight and took the same range. I got 470 yards and -1 inclination. The X-Sight SSS returned an up correction of 46.68". That's pretty good agreement for that range and a couple of degrees difference in inclination. Now here is the bad news... Using Applied Ballistics I set up an identical bullet profile. I set up the same firing solution and Applied Ballistics (what the pros use) gave me a come up of 9.4 MOA which agrees almost exactly with the ATN solutions. Then I enabled powder temperature compensation, Coriolis and Spindrift. The correct solution according to Applied Ballistics is up 14.5 MOA. So we are talking about an error of 5.5 MOA at 470 yards. That is 27 inches. That's two feet and three inches. Can these issues be corrected for in your long range shooting? YES but it is important that you know that these LIMITATIONS exist. Your X-Sight/LRF combination will get you just close enough at 400 yards to cripple your target if you don't understand the limitations of the ballistics calculator you are getting from ATN.If you don't mind my asking... what cartridge / bullet is that you are shooting? |
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oldspook
Super Contributor
Posts: 404
ATN Products Owned: Smart HD Optics
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Post by oldspook on Mar 22, 2017 13:57:36 GMT -8
The default profile in the X-Sight II is: G1 drag function 150 grain bullet 0.48 BC 1.5 inch sight height 2798.56 fps 99.52 yard zero The default profile in the Android LRF app is not identical but it is close so I just made the adjustments necessary to ensure that both of the profiles were identical and then performed a simple exercise. From my window I ranged a pole at 469 yards the inclination was -3 and let the app give me a solution. The solution was 37 up and we will ignore windage. At that range 37 1/4 MOA clicks equates to 45.406". I then fired up the X-Sight and took the same range. I got 470 yards and -1 inclination. The X-Sight SSS returned an up correction of 46.68". That's pretty good agreement for that range and a couple of degrees difference in inclination. Now here is the bad news... Using Applied Ballistics I set up an identical bullet profile. I set up the same firing solution and Applied Ballistics (what the pros use) gave me a come up of 9.4 MOA which agrees almost exactly with the ATN solutions. Then I enabled powder temperature compensation, Coriolis and Spindrift. The correct solution according to Applied Ballistics is up 14.5 MOA. So we are talking about an error of 5.5 MOA at 470 yards. That is 27 inches. That's two feet and three inches. Can these issues be corrected for in your long range shooting? YES but it is important that you know that these LIMITATIONS exist. Your X-Sight/LRF combination will get you just close enough at 400 yards to cripple your target if you don't understand the limitations of the ballistics calculator you are getting from ATN.If you don't mind my asking... what cartridge / bullet is that you are shooting? That is an imaginary cartridge that ATN is using as the default new profile in the X-Sight II. When you create a new profile these are the default values for that new profile. It serves the purpose is all. If you have a profile you want me to run specifically I'll be happy to do it. |
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oldspook
Super Contributor
Posts: 404
ATN Products Owned: Smart HD Optics
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Post by oldspook on Mar 22, 2017 14:38:25 GMT -8
I don't know what temperature compensation you are using, but combined coriolis/spin drift shouldn't approach 5.5 MOA at 470 yards. Coriolis + Spin drift for a RH 1:11 is about 1/10 MOA (1.7 inches) for the problem I was running. Coriolis windage error on the shot was 0.1 MOA right and spin drift error was 0.3 MOA right. So for windage the combined Coriolis and spin drift error was 0.4 MOA (2" right). I didn't mention L/R errors yesterday. Total error when you don't consider all those factors is 5.5 MOA U/D and 0.4 MOA L/R. Powder temperature correction was 5.4 MOA yesterday. Today it is a bit more than that as it is colder today. I guess the point I am trying to get across here is that we need to understand the limitations of the equipment. Many of the adopters of these sights are novice shooters and there isn't anyone trying to explain these limitations to them. They are being encouraged to believe after they have it zeroed they can just start knocking down White Tails or Hogs at 400 yards without additional preparations. That is going to lead to disappointed riflemen and crippled game. The ballistics calculators in these devices are just good enough to help the unwitting cripple a bear at 600 yards, every trackers nightmare. Many people would go out and zero their rifle and then shoot some targets at a few hundred yards on their range (if they have that) and they would be almost bang on. The average hunter would think they could repeat those hits tomorrow or next week if they used the same ammo, after all they have an ATN that calculates everything and puts the reticle right on the target. But tomorrow or next week the weather is going to change and the X-Sight doesn't know about that. It SHOULD know about weather as it has the sensors on board but I have seen zero evidence that it is actually using the data the sensors are providing in the actual shooting solutions that it provides. I'll be looking into that over the next week or so. |
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jdb
Contributor
Posts: 41
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Post by jdb on Mar 22, 2017 17:21:04 GMT -8
Question: My ATN seems to compensate for inclination...you see a correction in the coordinates as you raise or lower the barrel but I'm getting no coordinate correction for cant. Does your scope SSS compensate for the cant, if any, you have in a shooting position? Mine could be malfunctioning.
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oldspook
Super Contributor
Posts: 404
ATN Products Owned: Smart HD Optics
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Post by oldspook on Mar 22, 2017 20:02:46 GMT -8
Question: My ATN seems to compensate for inclination...you see a correction in the coordinates as you raise or lower the barrel but I'm getting no coordinate correction for cant. Does your scope SSS compensate for the cant, if any, you have in a shooting position? Mine could be malfunctioning. Regarding cant; I suspect that no correction is being done for cant. I believe that calculating that would be possible for sure but I bet that the developers are operating under the assumption that cant is a shooter error. I think they are actually running the SSS as a separate process so that it can compute for inclination as that changes. That being the case computing cant could and probably should be being done.I've never taken the time to check any of the environmental stuff beyond Coriolis and wind. It does wind pretty well. It is definitely not doing Coriolis even though it has all the data it needs to do that. It does not have all the data in needs to calculate spin drift but there are only 2 parameters it needs for that; rifling twist rate and bullet length. It could then calculate spin drift and "bullet jump" which is a function of spin, bullet length and crosswinds and is usually lumped in with spin drift.. Next week I'm going to start running tests to see what it is and is not actually using in the SSS. |
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