Trying to understand chrono readings

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litledab

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A friend brought out a chrono yesterday first time chroning anything for me .Got some weird reading I think. Was shooting 308 1/10 twist bolt,24 inch barrel ,lapua brass 210m fire formed ,neck tension .0005 168 horn bthp 42 gr varget and berger 168 vld target same load Average speed for both 3 rds each was 3100 ft/sec .No signs of primers flattening or even rippling, been shooting this load of a year, groups excellent all the way out to 600.Is this not way to fast for this load ??

Shot some factory loads out of other guns we had out and the readings came out below the box specs by 100/200 ft/sec on average.

Any idea what could be causing such high readings because I don't believe they r traveling that fast??

Thks Little
 
With having a chrono for several years I have more ???? Readings with sun problems or 99% of the time muzzle too close to the screen

now using my big feet and heal/toe 12 feet when I do my setup when the range is cold

next tip is to aim high --- on adverage bullet will be 2 plus inches below aim point with a scope
 
3100 with those bullets, that barrel length, and that powder charge is improbable.
With a long barrel, 155s and more powder, it can be done.
 
You should be around 2500-2600. With my 24" 1in11.25 5r. I was pushing 175 smk's at 2650 with 43.5 gr varget. Ive seen similar results on a chrony and 223 around 3100 when reality (measured by labradar) was 2700. It seems with the cheaper chronys you can really only rely on sd/es numbers.
 
See if you can borrow a second chrony, and shoot over them both (or one then the other). And try on an overcast day.
 
Is it a Chrony? If so, was it fully open? Not opening the unit fully will result in high readings, and lighting conditions can also cause errors.
 
sulisa said:
See if you can borrow a second chrony, and shoot over them both (or one then the other). And try on an overcast day.
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I just got a new Beta Master Chrony. First trip out it was overcast, but I got set up and just started when it started to rain. I finished up in the rain, but all readings were below what I expected.
Came home and read the good manual that came with the machine. Soon came across this, "Low light will result in low readings!"
Other instructions said to not use the milky diffuser on cloudy days. So I have decided to only chrono on cloud free days with the diffuser, as how do you guess what is suitable light and what is low light, on a dull day. I already know that in the sunshine one has to be careful to arrange it so the same light falls on each sensor.
I will guess that the high readings the OP got was caused by the machine being too close to the muzzle.
 
thks guys I don't know what the make is but I will give it another try this time going to put a 10 by 10 canopy above chrono .Yeh I knew those readings were high ,comparing my drops at different ranges I figured I should be around 2650f/s

thks Little
 
litledab said:
thks guys I don't know what the make is but I will give it another try this time going to put a 10 by 10 canopy above chrono .Yeh I knew those readings were high ,comparing my drops at different ranges I figured I should be around 2650f/s

thks Little
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A canopy? I don't think that is warranted if the unit has diffusers. Might be interesting to see what results you get from that though, but it might dull the light too much. 12 - 15 ft from and parallel to the muzzle should be adequate.
 
My own experiences have shown that setting up too close results in error readings. Having the sun at a sharp angle (sun rise or sunset), rather than directly overhead has caused higher than normal readings with my Chrony units.

I actually gave up on the Chrony brand , because of the issues with the readings changing with changing light conditions, and I purchased a Magnetospeed. Light does not effect a magnetospeed, and I don't need a cease fire at the range to set up or take down a Magnetospeed.
 
My own experience is that you have a pretty good idea what the speed should be. I actually shoot a 308 as one of my pratice guns with a 168 berger. And 4064 powder. It shoots at 2645 fps,( and that is pretty much max) its easy to verify the speed. Just put it into your ballistic program and go out and shoot some drops at long range. Most ballistic programs have a velocity calibration for fine tuning.
I have a couple of chrongraphs that I use, they can be very frustrating with light condtions either not reading or giving speeds that are not believable.
 
Welcome to the world of Chronys, the worlds most inaccurate method of measuring bullet speeds.............My old Chrony told me that the same load from the same rifle on two consecutive evenings somehow changed speeds by nearly 300 fps...........GARBAGE !!!
I understand this was not your chronograph and your buddy was probably trying to do you a favor, but this has been my experience with 3 different Chronys over the years. Which is why I own 2 Oehler model 35Ps now and I don't have to guess which reading is correct, or is it too bright or not bright enough...........
 
c-fbmi said:
Welcome to the world of Chronys, the worlds most inaccurate method of measuring bullet speeds.............My old Chrony told me that the same load from the same rifle on two consecutive evenings somehow changed speeds by nearly 300 fps...........GARBAGE !!!
I understand this was not your chronograph and your buddy was probably trying to do you a favor, but this has been my experience with 3 different Chronys over the years. Which is why I own 2 Oehler model 35Ps now and I don't have to guess which reading is correct, or is it too bright or not bright enough...........
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I did the same, but went one further with the LabRadar. The amount of time I save in set up and take down and transitioning between rifles is worth the premium price.

No adapters to loose or various parts/cables attached and or connected to chrony. I like knowing my data is close to 100% accurate as possible.
 
Most people who buy the F1 shooting chrony and basically any of the chrony line will eventually ditch it for a better, more accurate unit. The folding models are terrible, move it a little and the readings are completely different.
I went with an inexpensive Competition Electronics ProChrono, which is still sometimes intolerant if you don't shoot in the top third of the shooting area.
 
We once set up a test - firing over 2 Shooting-Chronys and one RCBS unit. Differences in velocity were scary, and not consistently different. In other words, the one which read higher on one shot might be slower the next. Lost my faith in all those units....
And consequently I wonder about the data one is getting from any chrony, but currently use an Oehler 35 and a Labradar. Haven't tested them together yet, but at least I have a little more trust in the data...
 
c-fbmi said:
Welcome to the world of Chronys, the worlds most inaccurate method of measuring bullet speeds.............My old Chrony told me that the same load from the same rifle on two consecutive evenings somehow changed speeds by nearly 300 fps...........GARBAGE !!!
I understand this was not your chronograph and your buddy was probably trying to do you a favor, but this has been my experience with 3 different Chronys over the years. Which is why I own 2 Oehler model 35Ps now and I don't have to guess which reading is correct, or is it too bright or not bright enough...........
Click to expand...

My Chrony F1 is the same. It seems to work well under ideal lighting conditions. Anything less and it generates a lot of useless data. I'm placing an order for a 35P next week as I've come to the same conclusion as you.

Chris.
 
I have done most of my chronographing with an Oehler and have records of it all.
The first thing one finds out is that there is often quite a difference between two rifles, as to the velocity they give. It is common to have two rifles of the same calibre, both in good condition, that vary 50 or 60 fps difference with identical loads. Worst I had was two excellent 30-06 rifles, each with very good bores, that differed just about 100 fps, with any identical load. As a point of interest here, the slow rifle can be shot at least as fast, or likely faster, than the fast rifle, just by putting more powder in the case!
I still have some of the rifles that I used the Oehler on. I can duplicate my records of the load as tested with the Oehler and test it with a Chrony. Under good conditions for the chrony the readings end up the same, within normal tolerances, plus or minus, that one would expect with the different lots of powder.
In using a Chrony, one certainly must pay attention to the conditions, mainly lighting.
My conclusion is if one is careful with the Chrony, its accuracy is all the average shooter needs to find out the true velocity of his bullets, at a fraction of the cost of an Oehler.
 
bsand said:
I did the same, but went one further with the LabRadar. The amount of time I save in set up and take down and transitioning between rifles is worth the premium price.

No adapters to loose or various parts/cables attached and or connected to chrony. I like knowing my data is close to 100% accurate as possible.
Click to expand...

is your labradar working in any conditions? heavy light or lowlight?
 
Yes, it doesn't rely on light but rather doppler radar microwaves. First day I took it out was supposed to rain 20mm. Every shot was recorded after I figured out proper placement of the unit.
 
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