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Bubble level for rifle
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<blockquote data-quote="4mesh063" data-source="post: 41003" data-attributes="member: 941"><p>Dave, </p><p></p><p>I just typed a lengthy explaination for this, edited it twice, and will now do it a third time. I think I have it. There are another 2 circles you need to add.</p><p></p><p>Your graphic is nice. But it does not show the origin from where the bullet came. Since this is confusing, I will break it into small parts to digest.</p><p></p><p>Your gun shoots a bullet drop of 3 units. Lets just say that your sight height is 1 unit for this example.</p><p></p><p>We need to establish where the barrel and scope are in the diagram. One of them is NOT stationary and that movement must be accounted for. The easy way is: (in my mind)</p><p></p><p>We will assume for this example, that the line of sight is allways absolutely dead level so that our scope and our point of aim are allways the same point as viewed from behind the gun. (both, allways the green dot) </p><p></p><p>If you place another circle around the green aim spot that is 1 unit in radius This is the starting location of the barrel for each shot. This takes into account the distance the barrel is below the scope. </p><p></p><p>The center of that circle is the actual centerline location of the scope exactly as we look at the target, our eye is always in the green circle, the scope, the POA, and our eye.</p><p></p><p>The Red circle needs to be 1 unit in radius smaller.</p><p></p><p>For shot # 1, (upright level fire) (the only easy one) The barrel is down at the bottom of our new circle, 1 unit below the scope and point of aim. The Bore LOS is now, 2 units above the green dot. The bullet impact is in the green circle as you show. </p><p></p><p>The trouble is, it only impacts 2 units below the bore los even though it has 3 units of drop. </p><p></p><p>Shot # 2. We rotate the gun clockwise 90 to the right but we rotate it around the sight line, so the barrel is what moves. This eliminates a lot of math. The barrel is now on the 1 unit radius circle you have added. </p><p>LEFT of the sight line by the 1 unit of sight height. </p><p></p><p>The Barrel is also 1 unit of elevation higher than it was for shot 1, so the bullet starts out, 1 unit vertically higher.</p><p></p><p>The Bore LOS is now, 2 units right of the point of aim. That establishes the lateral movement of the shot. The drop, is still the same and is 3 total units. Our impact is 3 units below the point of aim and 2 units right.</p><p></p><p>Unless I'm mistaken, it is forming an eliptical impact circle. But it gets worse later. Is it a teardrop?</p><p></p><p>Shot 3, has the barrel above the scope when firing at 180. It is now 2 units higher in starting elevation than it was for shot 1. Above the scope instead of below it. The bore LOS now is 2 units below the green circle. That plus 3 units of drop gives you an impact 5 units below the LOS (green dot).</p><p></p><p>I have read this statement to myself about a dozen times and can't help but beleive, something is wrong with it. If you have any ideas, I'm all ears. In shot 1, we deduct 1 unit of difference from Blos to POA/POI. In this shot, we don't. ????? Seem right.</p><p></p><p>With 3 units total drop, it arrives 5 units below the sight line. It is 5 units away from shot # 1. But only 2 units lower than shot 2. Shot 2 is 3 units lower than shot 1. Again, something seems wrong with this thinking. </p><p></p><p>Shot 4 is with the gun canted 270, or 90 to the left. The barrel is now 1 unit to the right of the scope. Again, the barrel starts off 1 unit higher in elevation than shot 1 and is 1 unit right of there. </p><p></p><p>This shot, impacts 3 units below the point of aim and 2 units to the left.</p><p></p><p>I think at this point, even if RSI is wrong, I would rather take thier word for it and miss, than try to think this through any more. Life is too short.</p><p></p><p>[ 03-07-2004: Message edited by: 4mesh063 ]</p></blockquote><p></p>
[QUOTE="4mesh063, post: 41003, member: 941"] Dave, I just typed a lengthy explaination for this, edited it twice, and will now do it a third time. I think I have it. There are another 2 circles you need to add. Your graphic is nice. But it does not show the origin from where the bullet came. Since this is confusing, I will break it into small parts to digest. Your gun shoots a bullet drop of 3 units. Lets just say that your sight height is 1 unit for this example. We need to establish where the barrel and scope are in the diagram. One of them is NOT stationary and that movement must be accounted for. The easy way is: (in my mind) We will assume for this example, that the line of sight is allways absolutely dead level so that our scope and our point of aim are allways the same point as viewed from behind the gun. (both, allways the green dot) If you place another circle around the green aim spot that is 1 unit in radius This is the starting location of the barrel for each shot. This takes into account the distance the barrel is below the scope. The center of that circle is the actual centerline location of the scope exactly as we look at the target, our eye is always in the green circle, the scope, the POA, and our eye. The Red circle needs to be 1 unit in radius smaller. For shot # 1, (upright level fire) (the only easy one) The barrel is down at the bottom of our new circle, 1 unit below the scope and point of aim. The Bore LOS is now, 2 units above the green dot. The bullet impact is in the green circle as you show. The trouble is, it only impacts 2 units below the bore los even though it has 3 units of drop. Shot # 2. We rotate the gun clockwise 90 to the right but we rotate it around the sight line, so the barrel is what moves. This eliminates a lot of math. The barrel is now on the 1 unit radius circle you have added. LEFT of the sight line by the 1 unit of sight height. The Barrel is also 1 unit of elevation higher than it was for shot 1, so the bullet starts out, 1 unit vertically higher. The Bore LOS is now, 2 units right of the point of aim. That establishes the lateral movement of the shot. The drop, is still the same and is 3 total units. Our impact is 3 units below the point of aim and 2 units right. Unless I'm mistaken, it is forming an eliptical impact circle. But it gets worse later. Is it a teardrop? Shot 3, has the barrel above the scope when firing at 180. It is now 2 units higher in starting elevation than it was for shot 1. Above the scope instead of below it. The bore LOS now is 2 units below the green circle. That plus 3 units of drop gives you an impact 5 units below the LOS (green dot). I have read this statement to myself about a dozen times and can't help but beleive, something is wrong with it. If you have any ideas, I'm all ears. In shot 1, we deduct 1 unit of difference from Blos to POA/POI. In this shot, we don't. ????? Seem right. With 3 units total drop, it arrives 5 units below the sight line. It is 5 units away from shot # 1. But only 2 units lower than shot 2. Shot 2 is 3 units lower than shot 1. Again, something seems wrong with this thinking. Shot 4 is with the gun canted 270, or 90 to the left. The barrel is now 1 unit to the right of the scope. Again, the barrel starts off 1 unit higher in elevation than shot 1 and is 1 unit right of there. This shot, impacts 3 units below the point of aim and 2 units to the left. I think at this point, even if RSI is wrong, I would rather take thier word for it and miss, than try to think this through any more. Life is too short. [ 03-07-2004: Message edited by: 4mesh063 ] [/QUOTE]
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