Re: How to adjust to shoot through chrono
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fred_C_Dobbs</div><div class="ubbcode-body">I usually shoot at public ranges, which means my time downrange to set up my chrono is limited. So the first thing I do is set up my rifle on the sandbags, back the scope down to its lowest magnification, and take aim through the scope at my target.
I've been too cheap to buy a laser bore sighter but I do carry a gooseneck AAA flashlight with a head that will fit inside the chamber of anything bigger than a .223. I switch it on and rest it inside the chamber, pointing down the bore. Then I go downrange to set up my chrono.
I keep a piece of cotton staging twine in my chrono box with a magnet tied to one and and a knot at the other. The knot is @10 feet. I stick the magnet on my muzzle and use the knot to measure the distance to the chrono.
I've got the diffuser rods on my chrono marked to help keep me from shooting it. The red marks are the HoB of my tallest scope/rings combo plus half an inch. The green mark is HoB of a rimfire plus 4", which should put me in the chrono's sweet spot for something with a short HoB.
I set the height of the chrono looking back at my rifle. Even though it isn't a laser, it's easy to tell from the flashlight illuminating the bore when the light is perfectly centered, meaning I'm looking straight down the bore. I use that as a reference for where to set the green stripe on the diffuser supports.
My camera tripod has a crank for extending the center post. I extend the legs so that the chrono won't be quite high enough, then use the crank to fine-tune the height.
When that's done, a quick peek through the scope tells me whether the horizontal crosshair is at least as high as the red marks (meaning I CANNOT shoot my chrono). This is why I backed down the magnification earlier, to maximize FoV so I could see the support markings.
If the range is cold when I get there (meaning I can't uncase my rifle), that's why I keep a 3-foot piece of 3/4" PVC tubing in the back of my station wagon. I put the tube down on the sandbags instead of the rifle, sight through it to align it on the target, and put the AAA flashlight inside it. Since the PVC tube is resting directly on the bags, it's an inch or so lower than the bore of a rifle would be so I align it with the red marks on the diffuser supports.
And I use JBM's online calculator to reverse-engineer my true MV from the reading the chrono gives @10 feet. </div></div>
That was very helpful. I have the same tripod, that I cam crank up or down.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: J.Myers</div><div class="ubbcode-body">This is the longest thread on shooting through a triangle that is feet from your rifle, pull bolt boresight or set scope to lowest power, at 3.5 I can see the chrono and aim down the middle that's all.
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It's interesting how people fucking shoot a chronometer 10 feet away from you trying to get some readings too then eh?
