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Rifles, Reloading, Optics, Equipment
Reloading
Chronograph Issue
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<blockquote data-quote="entoptics" data-source="post: 2935033" data-attributes="member: 104268"><p>You sure there's a problem with the chronograph? From what I've heard, 8800 fps is about right for the 6.5 Creedmoor... <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink ;)" loading="lazy" data-shortname=";)" /></p><p></p><p>I used optical chronies for years with good success, until I could finally afford a LabRadar, but wonky readings and errors were considered "you get what you pay for".</p><p></p><p>Because an optical chrony relies on the set distance between the two sensors, consistent readings require consistent setups.</p><p></p><p>1) Make sure to set it out far enough to avoid any muzzle blast effects, which IMO, were the #1 cause of error readings.</p><p></p><p>2) Carefully align the bullet path to the same height above the sensors every time (I made marks on the sky screen poles at the correct height for the scope-over-bore offset to send the bullet 3" above the sensors). Too high or too low can result in errors and/or inconsistent velocity readings. Different rifle/scope heights required different setup heights to maintain the same bullet to chronograph distance.</p><p></p><p>3) ALWAYS use the sky screens, regardless of light conditions.</p><p></p><p>4) Make sure to keep the sensors clean and free of dust/debris.</p><p></p><p>5) Ensure the chrony is parallel to the bore, both in the tilt and rotation axis. That meant actually using a bubble level or iPhone level on the barrel (while pointed to the target) and chrony, and matching the two bubble positions. Then sighting down the chrony to ensure it was not rotated at all.</p><p></p><p>6) Use a tape measure or piece of pre-cut string to make sure the chrony was the exact same distance from the muzzle every time. I chose 15' out, to avoid muzzle blast issues as mentioned above.</p><p></p><p>If you're already doing most/all of the above, it may be time to contact Caldwell and send her back to the mothership...</p></blockquote><p></p>
[QUOTE="entoptics, post: 2935033, member: 104268"] You sure there's a problem with the chronograph? From what I've heard, 8800 fps is about right for the 6.5 Creedmoor... ;) I used optical chronies for years with good success, until I could finally afford a LabRadar, but wonky readings and errors were considered "you get what you pay for". Because an optical chrony relies on the set distance between the two sensors, consistent readings require consistent setups. 1) Make sure to set it out far enough to avoid any muzzle blast effects, which IMO, were the #1 cause of error readings. 2) Carefully align the bullet path to the same height above the sensors every time (I made marks on the sky screen poles at the correct height for the scope-over-bore offset to send the bullet 3" above the sensors). Too high or too low can result in errors and/or inconsistent velocity readings. Different rifle/scope heights required different setup heights to maintain the same bullet to chronograph distance. 3) ALWAYS use the sky screens, regardless of light conditions. 4) Make sure to keep the sensors clean and free of dust/debris. 5) Ensure the chrony is parallel to the bore, both in the tilt and rotation axis. That meant actually using a bubble level or iPhone level on the barrel (while pointed to the target) and chrony, and matching the two bubble positions. Then sighting down the chrony to ensure it was not rotated at all. 6) Use a tape measure or piece of pre-cut string to make sure the chrony was the exact same distance from the muzzle every time. I chose 15' out, to avoid muzzle blast issues as mentioned above. If you're already doing most/all of the above, it may be time to contact Caldwell and send her back to the mothership... [/QUOTE]
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