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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
MERC - Maximum Effective Range Calculator
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<blockquote data-quote="speedengineer" data-source="post: 1969856" data-attributes="member: 112986"><p>I wanted to demonstrate the effect of each one of the uncertainty parameters individually. It is helpful to understand how each parameter is contributing to your shot dispersion at range. For this analysis, I am using a 6.5 PRC with 143 ELDX shooting at a 6.282" diameter target (1 MOA at 600 yards). <strong><span style="font-size: 12px">Edit (I might not have used the 6.5 PRC trajectory data for this example...might be 30-06. But, the same trends apply, despite the label on the plots. I also didn't update the 'title' field for each plot. But just read the descriptions above each image...</span></strong></p><p></p><p>MERC is able to consider uncertainty in five parameters:</p><ul> <li data-xf-list-type="ul">Rifle (and shooter) Precision (MOA)</li> <li data-xf-list-type="ul">Muzzle Velocity</li> <li data-xf-list-type="ul">Range Estimation</li> <li data-xf-list-type="ul">Wind Speed Estimation</li> <li data-xf-list-type="ul">Wind Angle Estimation</li> </ul><p></p><p>First, if you set all of the above uncertainties to zero, then all of your shots will hit exactly at your point of aim! You'll calculate a 100% hit probability, obviously.</p><p>[ATTACH=full]211525[/ATTACH]</p><p>[ATTACH=full]211526[/ATTACH]</p><p></p><p></p><p>Second, if you set only the "Rifle (and shooter) Precision" value to be 1 MOA, you'll get 90% hits at 600 yards. This is because we defined a 1MOA rifle as hitting a 1MOA target 9 out of 10 shots. Notice the hit distribution plot shows a scattered hit pattern that is centered around your point of aim.</p><p>[ATTACH=full]211527[/ATTACH]</p><p>[ATTACH=full]211528[/ATTACH]</p><p></p><p>Next, let's set the Rifle/Shooter Precision value back to zero. Actually, let's put it at 0.05 MOA (almost zero) since it'll make viewing the shot dispersion of the subsequent examples easier (shots won't all be on a single line).</p><p></p><p>Now, let's specify 10fps of muzzle velocity standard deviation. In this situation, with no wind, MVSD causes vertical dispersion on your target.</p><p>[ATTACH=full]211529[/ATTACH]</p><p>[ATTACH=full]211530[/ATTACH]</p><p></p><p>Now lets add in some 10mph crosswind from right to left. BUT, still zero uncertainty in wind speed estimation and wind angle estimation. With the addition of a crosswind, you can observe that SDMV results in hits that trend at an angle on the target! What this is showing is that when the rifle has a round that fires at a faster velocity than nominal, it hits the target high (less drop than anticipated) but it also hits that target to the upwind side! Since it was traveling faster, it experienced less wind drift than you held for. Rounds that leave the muzzle at a lower velocity than nominal will hit low, and be blown farther to the downwind side!</p><p>[ATTACH=full]211531[/ATTACH]</p><p>[ATTACH=full]211532[/ATTACH]</p><p></p><p>Set MVSD back to zero, and specify 10 yards of range uncertainty. Much like MVSD, range uncertainty causes vertical dispersion of the impact points. When the actual range is different from the range that you dialed for, your shot will hit the target either high or low.</p><p>[ATTACH=full]211533[/ATTACH]</p><p>[ATTACH=full]211534[/ATTACH]</p><p></p><p></p><p>...To be continued in the next post. I guess only 10 image attachments are allowed per post!</p></blockquote><p></p>
[QUOTE="speedengineer, post: 1969856, member: 112986"] I wanted to demonstrate the effect of each one of the uncertainty parameters individually. It is helpful to understand how each parameter is contributing to your shot dispersion at range. For this analysis, I am using a 6.5 PRC with 143 ELDX shooting at a 6.282" diameter target (1 MOA at 600 yards). [B][SIZE=3]Edit (I might not have used the 6.5 PRC trajectory data for this example...might be 30-06. But, the same trends apply, despite the label on the plots. I also didn't update the 'title' field for each plot. But just read the descriptions above each image...[/SIZE][/B] MERC is able to consider uncertainty in five parameters: [LIST] [*]Rifle (and shooter) Precision (MOA) [*]Muzzle Velocity [*]Range Estimation [*]Wind Speed Estimation [*]Wind Angle Estimation [/LIST] First, if you set all of the above uncertainties to zero, then all of your shots will hit exactly at your point of aim! You'll calculate a 100% hit probability, obviously. [ATTACH type="full" alt="1598818376646.png"]211525[/ATTACH] [ATTACH type="full" alt="1598818384255.png"]211526[/ATTACH] Second, if you set only the "Rifle (and shooter) Precision" value to be 1 MOA, you'll get 90% hits at 600 yards. This is because we defined a 1MOA rifle as hitting a 1MOA target 9 out of 10 shots. Notice the hit distribution plot shows a scattered hit pattern that is centered around your point of aim. [ATTACH type="full" alt="1598818536421.png"]211527[/ATTACH] [ATTACH type="full" alt="1598818548713.png"]211528[/ATTACH] Next, let's set the Rifle/Shooter Precision value back to zero. Actually, let's put it at 0.05 MOA (almost zero) since it'll make viewing the shot dispersion of the subsequent examples easier (shots won't all be on a single line). Now, let's specify 10fps of muzzle velocity standard deviation. In this situation, with no wind, MVSD causes vertical dispersion on your target. [ATTACH type="full" alt="1598818686163.png"]211529[/ATTACH] [ATTACH type="full" alt="1598818694998.png"]211530[/ATTACH] Now lets add in some 10mph crosswind from right to left. BUT, still zero uncertainty in wind speed estimation and wind angle estimation. With the addition of a crosswind, you can observe that SDMV results in hits that trend at an angle on the target! What this is showing is that when the rifle has a round that fires at a faster velocity than nominal, it hits the target high (less drop than anticipated) but it also hits that target to the upwind side! Since it was traveling faster, it experienced less wind drift than you held for. Rounds that leave the muzzle at a lower velocity than nominal will hit low, and be blown farther to the downwind side! [ATTACH type="full" alt="1598818839110.png"]211531[/ATTACH] [ATTACH type="full" alt="1598818846353.png"]211532[/ATTACH] Set MVSD back to zero, and specify 10 yards of range uncertainty. Much like MVSD, range uncertainty causes vertical dispersion of the impact points. When the actual range is different from the range that you dialed for, your shot will hit the target either high or low. [ATTACH type="full" alt="1598819110647.png"]211533[/ATTACH] [ATTACH type="full" alt="1598819117258.png"]211534[/ATTACH] ...To be continued in the next post. I guess only 10 image attachments are allowed per post! [/QUOTE]
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