Help! Velocity and target interpretation ... Chrony? Reloads? Heat?

I have fired thousands of test over a Chrony.

I do it on overcast days.

Pistol no closer than 15' and rifle no closer than 20'.

If I get close, strange things happen.

I would guess your variables are 100% muzzle blast.

Back off to 20' to prove it. Then try 15' if you like.
 
Well I was out at the range again and again had some bizarre Chrony results.

This time I placed the Chrony at 15’ from the muzzle (chord for the display won’t make it 20’). I did however forgot to swap the battery but I’ll test it later tonight and report back.

The first string of shots were really to warm up the barrel. I was firing at target from 200m-600m. They were all more or less in a straight line and all shots were over the Chrony. I wonder if small, and I mean small, changes in angle to the Chrony would account for major differences in velocity. For my original post all shots were fired at the same target from the same position.

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The second string of shots was to try this rifle at the 300yrds 1MOA challenge. I’m certain I had passed it before but figured I’d try it again. The Chrony results were more consistent but the speed were lower than I imagined.

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At least I passed the 1MOA challenge. A few gusts at 12 o’clock almost sunk me.

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So if the chord doesn’t go beyond 15’ and the instructions say 10’, how is everyone else using their Chrony???

It also doesn’t explain how one string was somewhat consistent while the other was not. Chance?
 
Just found an article on one of my favorite sites that answers a pile of questions:

https ://precisionrifleblog.com/2012/07/20/chronograph-accuracy-tips-15-practical-tips-to-increase-accuracy-reliability/
 
I wouldn’t mind trying one but from the videos I’ve seen, they seem a bit finicky when it comes to the installation. Labradars are quite a bit more expensive but I think I’d lean more towards one of them.

LabRadar is the way to go - even the savings in loading components alone can justify the cost difference...buy once, cry once.
 
LabRadar is the way to go - even the savings in loading components alone can justify the cost difference...buy once, cry once.

Yeah, I might have to start saving my pennies. The whole point of the Chrony is to get velocity data for my Kestrel so I can shoot long range. I test my groups on paper and figure out my velocity later. However, a more reliable and less finicky product might save me time and money.

5x+ the price is tough to swallow but at some point your time comes at a price.
 
The accuracy of the LabRadar is incredible and it can track even small (6mm) projectiles out to 80 yards so you can see the velocity degrade and can back compute ballistic coefficient under current conditions if you’re keen.
 
Yeah, I might have to start saving my pennies. The whole point of the Chrony is to get velocity data for my Kestrel so I can shoot long range. I test my groups on paper and figure out my velocity later. However, a more reliable and less finicky product might save me time and money.

5x+ the price is tough to swallow but at some point your time comes at a price.

Maybe you could post on CGN for someone in your area who has a LabRadar to meet you at the range to chrono some of your loads and to troubleshoot - I do this several times a year for my local club members.
 
Time to start trouble shooting:

Bought a Sinclair Expander Mandrel. Ran the Lapua brass through a Redding Series A full length sizing die without the expander ball. I was surprised to find that there was some variance in the neck tension. I’ll be very curious to see if having more consistent neck tension will show itself over the chronograph. Next time out I’ll be making sure the Chrony is set up perfectly.
 
Time to start trouble shooting:

Bought a Sinclair Expander Mandrel. Ran the Lapua brass through a Redding Series A full length sizing die without the expander ball. I was surprised to find that there was some variance in the neck tension. I’ll be very curious to see if having more consistent neck tension will show itself over the chronograph. Next time out I’ll be making sure the Chrony is set up perfectly.

In my experience neck tension is an important variable.
 
So, after picking up a Sinclair Expander Mandrel, I cleaned my brass with the ultrasonic cleaner, full length sized it with a Redding die without the expander ball (not the Type S) then ran the expander die. Same load data was used. Neck tension felt much more consistent this time. I went out to shoot a few groups and set up the Chrony.

First group was fired at 300m. There was very little wind and the Chrony was set up with the sun shades with no sun shining on the Chrony. The Chrony was 15’ from the muzzle. Chrony results were much more consistent and the group size was decent:

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Then I shot a group at 600m and immediately had several Err2 readings. I fiddled with the Chrony then figured it didn’t like having the sun shining it it’s general direction despite still being in the shade. I moved the Chrony under the roof of the firing point and started shooting again, this time 10’ from the Chrony. Results were again much more consistent:

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PROBLEM: the speeds were 100fps faster for the second group. The only real change was moving the rifle 5’ closer to the Chrony. I think the 2650fps is actually the correct velocity because when I entered it on the Kestrel it actually gave me the correct elevation call at 600m (4.8 MIL) whereas if I used the 2550fps the Kestrel called for 5.2 MIL and I was missing high.

Any idea what’s going on here?

I will say, I wasted a ton of time fiddling with the Chrony today and ended up with questionable data. I’m going to save up for something better.
 

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I wouldn’t mind trying one but from the videos I’ve seen, they seem a bit finicky when it comes to the installation. Labradars are quite a bit more expensive but I think I’d lean more towards one of them.

Magnetospeeds works great and if you fit the sensor at home before going to the range and establish which spacers work with that rifle. That way installing them back on the rifle at the range becomes less of a hassle.
 
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