My Chrony Results don't make sense

bmx280 · April 9, 2009, 06:13 PM

Guys, need some help with my chrony results...

shooting .223 (55gr fmj) out of a 16" bbl

The first two batches were BLC2 and the last two were H335. Check out the numbers with question marks. How could I be getting 4052 fps without blowing a primer and no signs of over pressure. Can my chrony be off or possible set up wrong?

ETA: that the unit was atleast 12 feet from the muzzle with the difuser attached.

Batch 1: 26 gr BLC2 , Wolf Primers

2652
2666
2661
2622
2639
2649
2647
2683
2663
2683

Batch 2: 25.5 gr BLC2 , Wolf Primers

2644
2625
2612
2648
2652
2588
2609
2617
2649
2606

Batch 3: 26 gr H335, CCI #41 Primers

3001
2992
3032
2999
2977
3000
3005
2996
2982
3008
3154 ???

Batch 4: 25.5 gr H335, CCI #41 Primers

2925
2897
2948
2907
2893
3127 ???
3106 ???
3532 ???
2935
2865
4052 ???

rwilson452 · April 9, 2009, 07:41 PM

With a Chrony Chronograph if the sun is shinning directly on the sensors you will get strange readings. Sunshine Day?

bmx280 · April 9, 2009, 07:50 PM

For the most part it was sunny with very few clouds. I thought the diffuser was supposed to help that though?

rwilson452 · April 9, 2009, 07:56 PM

it does but if the sun is at such an angle that it misses the deflector and shines directly on the sensor it overloads the sensor.

Quote:

For the most part it was sunny with very few clouds. I thought the diffuser was supposed to help that though?

ligonierbill · April 9, 2009, 08:03 PM

Checking my manuals (Speer #13 and Hornady 5th) your numbers seem in line and most of them are fairly consistent. Your H335 loads are at or near max, but it does look like you got a couple bad readings. On occasion, I have seen a goofy, totally unexplained reading on my chrono. Couldn't figure out why. You could be failing to trip the first light occasionally with such a small bullet. But I just write these off to gremlins. Double check everything in your loading process, and if you are sure about your loads, I would just scratch the odd readings.

PCJim · April 9, 2009, 09:45 PM

Do you recall any excessive recoil with your 4K+ chroneyed round? If that velocity is correct (which we all suspect it is not and is some chronograph error), the recoil should have been very noticably greater.

James R. Burke · April 10, 2009, 11:13 AM

ligonierbill is right. I also try to shoot thru the same spot aprx hieght wise, and make sure you keep the distance the same. Like he said now and then sun or some other factor just throws them off, and I would just write them off like he said. I believe Unclenick answered a question I had on my crony checking on if it was accurate. He suggested trying another crony, if you can find one or putting one behind the other.

April 9, 2009, 07:41 PM	#2
rwilson452 Senior Member Join Date: June 10, 2004 Location: Tioga co. PA Posts: 2,647	With a Chrony Chronograph if the sun is shinning directly on the sensors you will get strange readings. Sunshine Day? __________________ USNRET '61-'81

April 9, 2009, 06:13 PM	#1
bmx280 Junior Member Join Date: April 9, 2009 Location: NV Posts: 2	My Chrony Results don't make sense Guys, need some help with my chrony results... shooting .223 (55gr fmj) out of a 16" bbl The first two batches were BLC2 and the last two were H335. Check out the numbers with question marks. How could I be getting 4052 fps without blowing a primer and no signs of over pressure. Can my chrony be off or possible set up wrong? ETA: that the unit was atleast 12 feet from the muzzle with the difuser attached. Batch 1: 26 gr BLC2 , Wolf Primers 2652 2666 2661 2622 2639 2649 2647 2683 2663 2683 *Batch 2: 25.5 gr BLC2 , Wolf Primers* 2644 2625 2612 2648 2652 2588 2609 2617 2649 2606 Batch 3: 26 gr H335, CCI #41 Primers 3001 2992 3032 2999 2977 3000 3005 2996 2982 3008 3154 ??? Batch 4: 25.5 gr H335, CCI #41 Primers 2925 2897 2948 2907 2893 3127 ??? 3106 ??? 3532 ??? 2935 2865 4052 ???

April 9, 2009, 07:50 PM	#3
bmx280 Junior Member Join Date: April 9, 2009 Location: NV Posts: 2	For the most part it was sunny with very few clouds. I thought the diffuser was supposed to help that though?

April 9, 2009, 08:03 PM	#5
ligonierbill Senior Member Join Date: May 20, 2007 Posts: 2,457	Checking my manuals (Speer #13 and Hornady 5th) your numbers seem in line and most of them are fairly consistent. Your H335 loads are at or near max, but it does look like you got a couple bad readings. On occasion, I have seen a goofy, totally unexplained reading on my chrono. Couldn't figure out why. You could be failing to trip the first light occasionally with such a small bullet. But I just write these off to gremlins. Double check everything in your loading process, and if you are sure about your loads, I would just scratch the odd readings.

April 9, 2009, 09:45 PM	#6
PCJim Senior Member Join Date: July 11, 2008 Location: FL Posts: 570	Do you recall any excessive recoil with your 4K+ chroneyed round? If that velocity is correct (which we all suspect it is not and is some chronograph error), the recoil should have been very noticably greater.

April 10, 2009, 11:13 AM	#7
James R. Burke Senior Member Join Date: January 3, 2009 Location: U.P. of Mich/Quinnesec Posts: 1,897	ligonierbill is right. I also try to shoot thru the same spot aprx hieght wise, and make sure you keep the distance the same. Like he said now and then sun or some other factor just throws them off, and I would just write them off like he said. I believe Unclenick answered a question I had on my crony checking on if it was accurate. He suggested trying another crony, if you can find one or putting one behind the other.