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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Cold Bore Accuracy . . . Development
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<blockquote data-quote="MMERSS" data-source="post: 1068342" data-attributes="member: 63748"><p><span style="color: black"><span style="font-family: 'Verdana'">Accuracy is placing a bullet, or the center of a group, on the intended target. Cold bore accuracy is not potential group size, this is cold bore precision. Cold bore accuracy does not require a perfectly centered shot on the intended target only a requirement to hit a specific sized target.</span></span></p><p></p><p><span style="color: black"><span style="font-family: 'Verdana'">An example for big game hunting. Assume a 10" square or circular target is used to mirror the vital size of a broadside stationary big game animal. A cold bore accurate shot can hit the 10" target in any location with pending results assumed a clean kill regardless of where the target is hit. Any shot outside the 10" target may result in unwanted results and should be considered a non-accurately placed shot.</span></span></p><p><span style="color: black"><span style="font-family: 'Verdana'">I estimate cold bore accuracy in two parts, first what I "DO" know and second what I "DO NOT" know. The second is often the most important.</span></span></p><p><span style="color: black"><span style="font-family: 'Verdana'"></span></span></p><p><span style="color: black"><span style="font-family: 'Verdana'">"DO" knows</span></span></p><p><span style="color: black"><span style="font-family: 'Verdana'">Cold bore precision potential. This is established by shooting cold bore shots during practice from different firing platforms allowing the barrel to cool between shots. This is not successive fire group potential but rather cold bore precision potential. I may be able to shoot .5MOA cold bore groups on a calm day from a solid bipod with rest. I may only be able to shoot 1MOA cold bore groups on a calm day from an alternative rest such as a backpack without rear bag support. I note the precision potential from each type of shooting platform.</span></span></p><p></p><p><span style="color: black"><span style="font-family: 'Verdana'">MV SD. A chronograph can be used to record the MV of cold bore shots with the average velocity and SD noted. </span></span></p><p></p><p><span style="color: black"><span style="font-family: 'Verdana'">Atmosphere conditions such as absolute pressure, temperature and humidity. These can be measured with a calibrated weather station such as a Kestrel.</span></span></p><p></p><p><span style="color: black"><span style="font-family: 'Verdana'">Spin Drift. Ballistics computers can calculate SD corrections.</span></span></p><p></p><p><span style="color: black"><span style="font-family: 'Verdana'">Scope tracking and alignment. This is verified by conducting a tall target test.</span></span></p><p><span style="color: black"><span style="font-family: 'Verdana'">Ballistics calibration. Calibration or truing is conducted to establish calibrated muzzle velocity and range cards/ballistics drag profiles.</span></span></p><p></p><p><span style="color: black"><span style="font-family: 'Verdana'">The size of vitals of the game animal hunted. 10" was used in this example.</span></span></p><p></p><p><span style="color: black"><span style="font-family: 'Verdana'">Range to target or animal. A good range finder properly used provides this information.</span></span></p><p></p><p><span style="color: black"><span style="font-family: 'Verdana'">"DON'T" knows</span></span></p><p><span style="color: black"><span style="font-family: 'Verdana'">THE WIND- estimating how the wind will be acting the entire path of the bullet is often the predominant factor causing a miss. We are all human and can only estimate within a certain degree the average intensity and direction the wind will be blowing when the shot is taken. What we can do is estimate the uncertainty or variable of the wind and try to make the shot as close to this estimation as possible. An average wind speed and direction can be corrected for with variances noted. For example, assume hunting on a flat with the wind predominantly blowing from 3 o'clock. A Kestrel can be used to measure the variance. Look at the Kestrel readings. If the readings fluctuate between 4 and 10 MPH I will assume a 7 MPH average with a plus or minus 3 MPH uncertainty. I will make certain to adjust my range to ensure this uncertainty still leaves room for the bullet to strike the intended target. I "DO NOT" know the exact behavior of the wind but I can apply wind uncertainties to ensure the bullet still strikes the vitals.</span></span></p><p></p><p><span style="color: black"><span style="font-family: 'Verdana'">I now use Applied Ballistics Analytics to enter the "DO" knows listed above with the "DO NOT" knows listed below with corresponding range. The solver will predict a cold bore accuracy shot percentage based on this information. The solver may predict a 75% chance of hit. Assuming a hunter is using the guideline "9 shots out of 10" centering the vitals as go/no-go criteria for the shot, the 75% estimate indicates the corresponding range is too far for the current conditions. The solver will additionally list the range for 90% certainty and so on. I use the solver to color code range percentage estimates on range cards. This way if I'm hunting and have a shooting platform providing 1 MOA precision potential with 2 MPH crosswind uncertainty I have a MAXIMUM EFFECTIVE RANGE (MER) annotated for the current estimated conditions and ensure I am not shooting past this range.</span></span></p><p></p><p><span style="color: black"><span style="font-family: 'Verdana'">MER parallels cold bore accuracy, ensuring a shot can be made with ensuing certainty to hit the intended sized vitals under the current environment.</span></span></p></blockquote><p></p>
[QUOTE="MMERSS, post: 1068342, member: 63748"] [COLOR=black][FONT=Verdana]Accuracy is placing a bullet, or the center of a group, on the intended target. Cold bore accuracy is not potential group size, this is cold bore precision. Cold bore accuracy does not require a perfectly centered shot on the intended target only a requirement to hit a specific sized target.[/FONT][/COLOR] [COLOR=black][FONT=Verdana]An example for big game hunting. Assume a 10” square or circular target is used to mirror the vital size of a broadside stationary big game animal. A cold bore accurate shot can hit the 10” target in any location with pending results assumed a clean kill regardless of where the target is hit. Any shot outside the 10” target may result in unwanted results and should be considered a non-accurately placed shot.[/FONT][/COLOR] [COLOR=black][FONT=Verdana]I estimate cold bore accuracy in two parts, first what I “DO” know and second what I “DO NOT” know. The second is often the most important.[/FONT][/COLOR] [COLOR=black][FONT=Verdana] “DO” knows[/FONT][/COLOR] [COLOR=black][FONT=Verdana]Cold bore precision potential. This is established by shooting cold bore shots during practice from different firing platforms allowing the barrel to cool between shots. This is not successive fire group potential but rather cold bore precision potential. I may be able to shoot .5MOA cold bore groups on a calm day from a solid bipod with rest. I may only be able to shoot 1MOA cold bore groups on a calm day from an alternative rest such as a backpack without rear bag support. I note the precision potential from each type of shooting platform.[/FONT][/COLOR] [COLOR=black][FONT=Verdana]MV SD. A chronograph can be used to record the MV of cold bore shots with the average velocity and SD noted. [/FONT][/COLOR] [COLOR=black][FONT=Verdana]Atmosphere conditions such as absolute pressure, temperature and humidity. These can be measured with a calibrated weather station such as a Kestrel.[/FONT][/COLOR] [COLOR=black][FONT=Verdana]Spin Drift. Ballistics computers can calculate SD corrections.[/FONT][/COLOR] [COLOR=black][FONT=Verdana]Scope tracking and alignment. This is verified by conducting a tall target test.[/FONT][/COLOR] [COLOR=black][FONT=Verdana]Ballistics calibration. Calibration or truing is conducted to establish calibrated muzzle velocity and range cards/ballistics drag profiles.[/FONT][/COLOR] [COLOR=black][FONT=Verdana]The size of vitals of the game animal hunted. 10” was used in this example.[/FONT][/COLOR] [COLOR=black][FONT=Verdana]Range to target or animal. A good range finder properly used provides this information.[/FONT][/COLOR] [COLOR=black][FONT=Verdana]“DON’T” knows[/FONT][/COLOR] [COLOR=black][FONT=Verdana]THE WIND- estimating how the wind will be acting the entire path of the bullet is often the predominant factor causing a miss. We are all human and can only estimate within a certain degree the average intensity and direction the wind will be blowing when the shot is taken. What we can do is estimate the uncertainty or variable of the wind and try to make the shot as close to this estimation as possible. An average wind speed and direction can be corrected for with variances noted. For example, assume hunting on a flat with the wind predominantly blowing from 3 o’clock. A Kestrel can be used to measure the variance. Look at the Kestrel readings. If the readings fluctuate between 4 and 10 MPH I will assume a 7 MPH average with a plus or minus 3 MPH uncertainty. I will make certain to adjust my range to ensure this uncertainty still leaves room for the bullet to strike the intended target. I “DO NOT” know the exact behavior of the wind but I can apply wind uncertainties to ensure the bullet still strikes the vitals.[/FONT][/COLOR] [COLOR=black][FONT=Verdana]I now use Applied Ballistics Analytics to enter the “DO” knows listed above with the “DO NOT” knows listed below with corresponding range. The solver will predict a cold bore accuracy shot percentage based on this information. The solver may predict a 75% chance of hit. Assuming a hunter is using the guideline “9 shots out of 10” centering the vitals as go/no-go criteria for the shot, the 75% estimate indicates the corresponding range is too far for the current conditions. The solver will additionally list the range for 90% certainty and so on. I use the solver to color code range percentage estimates on range cards. This way if I’m hunting and have a shooting platform providing 1 MOA precision potential with 2 MPH crosswind uncertainty I have a MAXIMUM EFFECTIVE RANGE (MER) annotated for the current estimated conditions and ensure I am not shooting past this range.[/FONT][/COLOR] [COLOR=black][FONT=Verdana]MER parallels cold bore accuracy, ensuring a shot can be made with ensuing certainty to hit the intended sized vitals under the current environment.[/FONT][/COLOR] [/QUOTE]
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