Hey everyone. I'm not sure if this is the right spot for this post, so please move if needed. Yesterday I was practicing before an elk hunt I have coming up in January. It was about 10 degrees and I wanted to see how much slower my velocities would be. I was shooting my 7 mag loaded with 68.8 gr H1000 and 162 gr Eld-x. I was shooting thru a Prochrono and it actually showed 30-50 fps FASTER than when I was shooting the same load the week before at 35 deg. I wasn't expecting much velocity shift and definitely not faster at cold temps from what I have read. At first I was concerned I might be over pressure pushing 3065 FPS, but there were no signs on the brass or bolt lift. I shot at 480 yds with my previous dope and 3017 FPS and hit perfect on a 10" steel 3 times so I don't think I was actually getting the faster velocities. I was shooting prone and there was snow on the ground and it was very bright. So I'm wondering if this could make the chrono read faster? The low battery indicator came on about half way through but I didn't notice a change in velocity due to that. What do you guys think? Is my chrono on the fritz?
Chrono Issue?
- Thread starter Jaredk03
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ShtrRdy
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I'll be interested if anyone has a definite answer to this. I've noticed an increase in velocity reading when the temps are single digit and I'm using a Magnetospeed.
It's nice that you could check your drops on a more distant target to double check.
It's nice that you could check your drops on a more distant target to double check.
bgbuck153
Well-Known Member
When you shot at 35 degrees was it cloudy or sunny? I have a prochrony and I stopped using it because as the sun rose across the sky my velocities would change and at times considerably. A cloud would roll they and change it again. That's why I'll be buying a Labrador in the very near future
Interesting...What powder were you using that gave a velocity increase with single digits? I didn't know if this could happen as I have only read about velocity decreasing with temp, but I have only been reloading less than a year. If it's possible, maybe I was getting higher velocities? Just ran the higher velocity drops and it would have only changed my impact an inch or two so I guess it's possible. I also shot my 6.5 CM with factory 143 eldx precision hunter ammo thru the chrono and it showed about 100 FPS slower than the week before.
It was cloudy when it was 35. This time it was 10 deg and sunny. My buddy has a Labradar and it's nice, but it sure eats batteries!
bgbuck153
Well-Known Member
Thanks, I didn't realize the Prochrono had a low temp limitation. Maybe I could test this by shooting some frozen ammo thru it on a warmer day and see if I get a different result?
dfanonymous
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Shooting prone and shooting on bench changes muzzle velocity too according to a study by sniperhide
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Wedgy
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Too many variables with a cheap chony, they raise more questions than they answer. Get a Labradar or Magnetospeed, but the Magnetospeed can change the point of impact and/or accuracy depending on the rifle. I gave up my Magneto in favor of the Labradar after running them simultaneously and seeing they are both accurate. Other than price I don't see any drawback of the Labradar.
Wedgy
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Yes, the best thing that ever happened to mine was when I loaned it to a friend and he shot it, ending my misery.
Schnyd112
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therifleman556
Well-Known Member
I understand you've uncovered the issue, but you also raised the point about shooting on snowy ground. I once checked some 7 mag loads on a very sunny day with the chronograph sitting on concrete. So much light must've confused the unit because those loads clocked 4400 fps. I still have fingers to type this so I'm guessing the chrony was not functioning correctly.
