Resettting and\or Recalibrating an F1 Chrony

[338winmag]

after comparing side by side with another chronograph, the difference is about 170 FPS with most differnt reloads. Problem is we are not sure which one is most accurate unless we bring into play a third chronograph. When we compare expected velocities with manuals, some are close to one chrongraph and others are close to the other.

Anyone have any suggestions how to reset a chrony or how to find which one is the most accurate?

Thanks
338winmag

 

[DrMike]

You're best off sending it back to the Shooting Chrony people for recalibration.

 

[FOTIS]

I agree. They are a first rate company.

 

[SJB358]

after comparing side by side with another chronograph, the difference is about 170 FPS with most differnt reloads. Problem is we are not sure which one is most accurate unless we bring into play a third chronograph. When we compare expected velocities with manuals, some are close to one chrongraph and others are close to the other.

Anyone have any suggestions how to reset a chrony or how to find which one is the most accurate?

Thanks
338winmag

Steve take a 22LR along to the range and test it using the advertised speed. 22 ammo from good companies is usually pretty close to advertised specs out of most common rifles. Not perfect but it could help verify what is what before you send it back. Scotty

 

[338winmag]

excellent Scotty!!!

...then if needed, it goes to the Chrony people.

thanks everyone
steve

 

[FOTIS]

Something else---obvious but has nailed me before.

It is opened all the way?

When you screw in the adapter that goes on the tripod and it is not all the way opened you will get false readings.

 

[338winmag]

I also ran into not having the chrony perfectly flat at one time but I make absolutely sure now.

Came back from the range and tried Scotty's testing suggestion.
I used two different 22lr rounds.

For the one advertising 1260 FPS
1295, 1248, 1285, 1282, 1225, 1265, 1270, 1288 --> average 1269.75

For the one advertising 1280 FPS
1333, 1300, 1285, 1292, 1306, 1293, 1306, 1361 --> average 1309.5


Now seeing those results and understanding a few thoughts, tell me if one might think my chrony is not correctly calibrated.

1. Compared to another persons brand new chronograph rounds from a 300 WM and a 30-06 appear to be about 170 FPS faster than the other chronograph.

2. It does seem that many loads that I build reach or exceed the "book" powder to speed ratios. Not by alot but here are a few examples. (I do understand those numbers are for example only)

A. 7mm Rem Mag - 160 Sierra GK BT - H4831sc
Sierra --> 60.8 = 2900
My Load --> 60.5 = average 2939

B. 30-06 - 165 Sierra GK BT - H4350
Sierra --> 54.1 2800
My Load --> 54.2 = average 2830

C. 270 Winchester - 150 Hornady Interlock BT - H4831
Hornady --> 55.0 = 2700
My Load --> 54.0 = average 2750

Whats incredible is I fired 6 rounds of 270 Winchester over the counter Super X 150 grain ammo. This ammo registerd an average of 2980??? Is that possible or is it my chronograph?

Thanks all
338winmag

 

[DrMike]

Given the information provided, I'd suggest that your data falls within the confidence level anticipated. As for the factory ammo, what velocity did the box suggest, or did it suggest a velocity? To satisfy your mind, however, it is always possible to send the Chrony back to Shooting Chrony with a request that it be recalibrated. Then, you'll know for certain.

 

[338winmag]

There was no suggested velocity on the box. The ammo shot horribly out of this one rifle. If you can believe this --> 7"+ groups of three. This validates the rifle's owner who stated that the groups were about 5" groups with this ammo. Just hard to believe how bad that ammo is in this rifle.

I am going to ask the owner of the new chronograph to test some of the same ammo\same rifle with his chronograph. I am thinking if he is significantly lower than manufacturer's stated velocity, then it might be his. Will know Wednesday or Thursday.

As always, thanks Mike!

 

[FOTIS]

I agree. It seems correct.

 

[SJB358]

I also ran into not having the chrony perfectly flat at one time but I make absolutely sure now.

Came back from the range and tried Scotty's testing suggestion.
I used two different 22lr rounds.

For the one advertising 1260 FPS
1295, 1248, 1285, 1282, 1225, 1265, 1270, 1288 --> average 1269.75

For the one advertising 1280 FPS
1333, 1300, 1285, 1292, 1306, 1293, 1306, 1361 --> average 1309.5


Now seeing those results and understanding a few thoughts, tell me if one might think my chrony is not correctly calibrated.

1. Compared to another persons brand new chronograph rounds from a 300 WM and a 30-06 appear to be about 170 FPS faster than the other chronograph.

2. It does seem that many loads that I build reach or exceed the "book" powder to speed ratios. Not by alot but here are a few examples. (I do understand those numbers are for example only)

A. 7mm Rem Mag - 160 Sierra GK BT - H4831sc
Sierra --> 60.8 = 2900
My Load --> 60.5 = average 2939

B. 30-06 - 165 Sierra GK BT - H4350
Sierra --> 54.1 2800
My Load --> 54.2 = average 2830

C. 270 Winchester - 150 Hornady Interlock BT - H4831
Hornady --> 55.0 = 2700
My Load --> 54.0 = average 2750

Whats incredible is I fired 6 rounds of 270 Winchester over the counter Super X 150 grain ammo. This ammo registerd an average of 2980??? Is that possible or is it my chronograph?

Thanks all
338winmag

Steve, to ME, your chrono looks within specs to me. I would run with your numbers and be happy. I like being able to validate using a 22. Seems to be cheap and create some confidence in your load work. Scotty

 

[super-7]

Whenever I am using the chrony for loads, I throw the 17 hmr in, for verifying . the 17 gr bullet is 2550, or there abouts, if I'm within reason with the 17, I proceed to chrono the rest of my hand loads, if something is off with the 17, I'll repostion, remove replace battery, fix sun shades or whatever till the 17 is close.

 

[RiverRider]

I have had some unusual readings using a Chrony at times in the past, and I think it was due to lighting conditions most often. Once recently when it was late in the day and the sun was very low, I got weird readings and decided to just shut it down. It seems that when the sun is nearly overhead and the sun can shine right straight down into the sensor slots, there can be difficulties also. I use pieces of cardboard like matchbook covers, or whatever I can find, to shade the sensor slots and things seem to work a little better.

 

[Oldtrader3]

I have recorded errors with my Chrony Beta Master with both my 7mm Rem Mag and my .340 Weatherby. I ended up moving the screens back to 15 feet instead of 10 feet and that seemed to take care of the strange readings that I was getting. I suspect too much vibration and ejecta was giving me phony readings with my Chrony.

My chrony seems to read fairly close to other machines that I have checked some of my same loads with. If I am within one sigma of variance with another machine, I feel that it is close enough to reality for my purposes.