Crazy Chrony

trevort · Post by **trevort** » Mon Feb 05, 2007 1:00 pm

Or shoddy operator?

Bought a second hand F1 shooting Chrony which looks in new condition.
Set It up and used it yesterday for the first time. Was careful to make sure it was fully opened and set up 3 mtres from muzzle. Tried 223, 6/250 and 204.

Had developed 223 loads of 50gn BK and 26gn 2206 .
Clocked an average of 3360 fps. That seemed Ok as this was max load.

I read this powder is being discontinued so tried same projie with ADI 2206H. 27.6gn clocked 3475 3477 3483 and 3512. That seemed high to me. Rifle is a CZ 527 varmint laminate.

The shooter next to me asked to try his 22/250. He got 3580 with a factory round and 3700 with a handload. These seemed in the expected range for a 22/250 although I forgot to ask what charge and projie.

I then tried the 6/250. I loaded from Hodgdons data on their website. They used a 24 inch 1/8 twist while I have a 26 Lilja 1/12. I was clocking the speeds as breaking in the Barrel ( ran out of time to try for any meaningful accuracy groups). Their max load for a 70 gn sierra HPBT was expecting 3436 fps.

I got 3691 3672 3687 from the max load and 70 NBT. Could 2 inches of shiny smooth barrel and a projie with a higher BC make this difference?

I then tried the 65 Vmax. I loaded between the 60 and 70 gn loads as they didnt list this weight . 2 shots at 36.5 got 3757 and 3752
one shot at 37gn got 3805.

Next came the 204. My 39 Bk load is over max at 27.9 (Nick Harvey manual now lists max at 28 tho) 2206h. I expected it to be fast and got 3951 3933 3903 3911 and 3924. Do these sound feasible. I thought so. Next I tried the 40 NBT with 27.8gns 2206h. I thought that since the charge was less (even tho just a 1/10th of a gn) and the projie fractionally heavier that these should be slower.

NO way. I got 3965 4000 3952 3991 4003 3988.

So some loads clocked seemed in the expected ball park while others seem too high.

What do you think? Should I accept and be pleased with these speeds or is the chrony unreliable or is there something I could have done wrong setting it up.

Wind was very strong but blowing directly across the range so would not think that was a factor. It was 32 c the Chrony was in the sun but the firing line and ammo were under shade.

Opinions or advice welcome

steven · Post by **steven** » Mon Feb 05, 2007 2:02 pm

Trevort,

Welcome to the world of ballistics....Your chrony needs to be in shade but not undercover or make sure the diffuser screens cover the skyscreens if out in the sun....also if you have a rimfire, check the speed of some low velocity target ammo...most target stuff is doing 1080fps so if its in that ballpark you are doing something right...I have a chrony and have set it up inline with another brand and only averaged about 10fps difference between the 2.

Steve

300RUM · Post by **300RUM** » Mon Feb 05, 2007 9:21 pm

I had 2 F1 chrony's at one stage and when placed in line with one another there was 1% difference btw the 2. But swap them around and the 1% difference went the other way. And I also check mine occasionly with rimfire ammo. Yeah they don't like to look at the sun or blue skys but white cloud seems to work fine if not using the screens. I never had what i would consider an inaccurate reading by not using the sreens it would just come up with an error if there was no clouds or shade over the chrony at the time. Damn good things I reckon.
Regards Brett

bushchook · Post by **bushchook** » Mon Feb 05, 2007 9:38 pm

I made up a large skyscreen for mine as found it unreliable in bright sunlight with the originals . Useless within an hour of sunup or sundown . Read somewhere that a strip of frosted sticky tape over the openings at either end works but have never tried it .

Con · Post by **Con** » Thu Feb 08, 2007 9:45 pm

Trevort,
Bushchook's said it all! Chronys are notorious for high readings particularly under direct sunlight and when placed too close to the muzzle of the rifle. I used to read 4000+fps from a 458Lott if closer than about the regulation 15feet, whilst a Nagant carbine and ex-mil ammunition played pure havoc with it.

Make yourself some larger diffuser screens and cover the sensor slots with a sheet of translucent cellophane. It seems to make them a bit more consistent.

And try not to shoot them like I did at the start of chronographing my 375-08. Luckily I just winged it

... but no more skyscreens until I make some more.
Cheers...
Con

ogre6br · Post by **ogre6br** » Thu Feb 08, 2007 10:14 pm

now you know why I never used it
I'm a shit shot at the best of times imagine my "confidence" boost after I pinged a chrony a 15 feet.

I'd hand my head in shame and prolly give up shooting for a while.

I have shot a CB ariel at about 4 feet while shooting over the cab one night. but even then I only winged it.

later
p

trevort · Post by **trevort** » Fri Feb 09, 2007 10:43 am

I once shot the wing mirror off a Magna we were spotlighting from(company car so 4WD version

) Rabbit was so close he nearly filled the whole scope but I forgot the scope is higher than the barrel, which happened to be sitting just in front of the corner of the wing mirror! Hopefully I wont be posting pictures of your old chrony "dead" Ogre.

Might take it to the farm with me Monday. No suitable rests to try to shoot the new rifle for accuracy but could try the chrony further away and "benchmark" it with some 22lr.

Post by **kjd** » Fri Feb 09, 2007 10:57 am

trevort wrote:I once shot the wing mirror off a Magna we were spotlighting from(company car so 4WD version ) Rabbit was so close he nearly filled the whole scope but I forgot the scope is higher than the barrel, which happened to be sitting just in front of the corner of the wing mirror! Hopefully I wont be posting pictures of your old chrony "dead" Ogre.

Might take it to the farm with me Monday. No suitable rests to try to shoot the new rifle for accuracy but could try the chrony further away and "benchmark" it with some 22lr.

What did your boss say about that???

trevort · Post by **trevort** » Sun Feb 11, 2007 5:12 pm

was my bosses car! he was driving

*removed by mod to save your bosses @$$

*

trevort · Post by **trevort** » Wed Feb 14, 2007 11:47 am

set the chrony up at a farm Monday. Tried one shot with the 6/250 that read 3740fps (about 100fp less than same load on range trip). Had it about 15 feet from muzzle.

next shot didnt read. Put in new battery. No reading for 3 shots then 'error 2' was displayed. Might need to find instructions to see what that means.

glenn asher · Post by **glenn asher** » Fri Feb 16, 2007 9:40 am

Error 2 means the bullet didn't register at the second screen, you'll have to check your alignment carefully. Happens to me all the time!

Kenny · Post by **Kenny** » Sat Feb 17, 2007 11:53 am

Trevort,

I borrowed a mates chrony awhile back and got similar problems to what you are having.

I frigged about changing batteries, distances and adjusting angles etc & I also got the error

I had just about given up thinking one of us was rooted...then I sat a piece of whiteboard over the top of it on the poles......and violla it worked.

Now I dunno if the sensor was missing the sky screen or just wtf was up with it but it performed flawlessly.

I also played at home in the garage to get it going using the slug gun to save on pills, powder and time. Even a rock thrown through worked a few times

Not saying it will fix your problem but worth a try

KY

trevort · Post by **trevort** » Sat Feb 17, 2007 3:29 pm

Thanks glenn and Kenny.

Kenny what happened to your avatar? I miss her already

Knackers · Post by **Knackers** » Sat Feb 17, 2007 4:54 pm

Me too Kenny, bring her back.

Kenny · Post by **Kenny** » Sat Feb 17, 2007 8:57 pm

Fellas......well there was a couple of reasons I liked her, probably the same ones you blokes have

.....but in the end like most toys I got sick of it

That + I reckon she was not quite fitting into the varminter theme......if she was layin' on the ground all spread out like a busted rabbit.......maybe it would have been better

Good luck with the chrony Trev

KY

AusVarmint

Crazy Chrony

Crazy Chrony