Chrony Question.

[RAF]

This evening I was at the range and took my 22-250 with me to shoot along with a 30-06. I had to re-zero the 22-250 'cause I used that scope to work up a load for my new 300 WSM. Anyway, I was also interested to see what velocity I was getting with it. I'm shooting 40 grain V-Max over 41.5 grains of H380. I guessing it's about 4000 but want to make sure. Well, the Chrony wouldn't give me a reading on these. Any ideas why. Seems I tried this years ago, with another Chrony, and got the same results. I did shoot some larger 55 grain bullets over it and they registered but not these little and faster ones. I should point out that these are moly coated but can's see how that would make a difference. Anyway, any help would be

 

[nugbuk]

There is no reason why Chrony will not read your fast and molly coated bullets.
1. Make sure you are shooting right over center of Chrony?s ?eyes?.
2. Make sure you have dispersion screen installed.
3. Try play with the height of the trajectory over ?eyes?. Most likely you need to shoot lower.
I hope this will help.

 

[jcchartboy]

2. Make sure you have dispersion screen installed.

I agree with Nug on adjusting the sky screen....However, I should add that I've also had luck removing the sky screens completely on a few occasions. In fact with my setup I have actually had the most consistent success with no sky screens while the chrono was in the Grouse MZ box with the Lexan top on.

Moral of the story...don't be afraid to try multiple configurations...sooner or later you will find a good combo that works...

JC

 

[Rifleman]

But don't shoot it :lol:

 

[jcchartboy]

But don't shoot it :lol:

At least not until you have expended all other options.... :nono:

JC

 

[RAF]

. The sky screens weren't on it at the time. Haven't used them since first time out. Kept blowing them off from the muzzle blast. I thought about putting them on but didn't. It worked fine for my 30-06 before and my friends 7mm rem mag after. I did move it up a little and estimate I was shooting about 3 -- 4 inches over it. Looked pretty much centered. I'll have try again with the screens on.

 

[Rifleman]

Ah ha Raf you tell on yourself. That is the reason your chrony won't read the 22-250 with the smaller bullet I bet, your too close. If you are blowin off the shy screens from muzzleblast you are too close. Back that chrony off about 15 feet and shoot through it and I bet you will get more consistent readings and by experimenting with the sky screens on and off you will be able to get a reading with the 22-250 and smaller bullets. All that gas from the muzzle blast is full of microscopic particles, and all together they make a cloud that produces a shadow, your chrony reads shadows and that little bullet is gettin lost in the crowd. Thats the "technical" explanation.
BTW did I ever tell you about the time my buddy shot his chrony with a 50 BMG ? It was a hoot, he shot his chrony a good 100 yds down range, I never laughed so hard in all my life.

 

[nugbuk]

Ah ha Raf you tell on yourself. That is the reason your chrony won't read the 22-250 with the smaller bullet I bet, your too close.

That is exactly what is happening here. After you move chrony to 12 to 15 feet from the bench you should recheck you other loads since reading may be false from expending gases.

 

[big6x6]

Could be any one of five things, beginning with the most likely:

1. Light conditions. Try with both the diffusers on and with them off. I ALWAYS start with them on. Place your Chrony far enough away(usually about 8-10 feet) so that the diffusers aren't blown off. But the general rule is cloudy-diffusers off, sunny-diffusers on. Another hint is to try putting a piece of Scotch tape over each photo sensor with NO diffusers.

2. Weak or dead battery. I keep 4 or 5 brand new alkaline 9 volt batteries in my truck at all times just for this reason.

3. Not shooting the correct height over the photo sensors. Shooting Chrony recommends shooing thru a "window" that from 4-6 inches over the photo sensors. Many put electrical tape on the diffuser rods at 4 and 6 inches over the photo sensors to help with this.

4. Dirty photo sensors. I clean with with a Q-tip.

5. The Shooting Chrony itself. I've owned three of 'em and it is by FAR the most picky chronograph I've ever used.

 

[RAF]

Lots of good suggestions. Where do I start. The instructions said should be 10 feet from the muzzle and it's probably set up about 12 feet. The sky screens that were blowing off were from the 300 WSM. Probably wouldn't happen with the 22-250. I'll try them. Batteries are almost new, used 3 times. Will check the lenses but don't expect them to be dirty of dusty. Light conditions were good. It read bullets before and after shooting the 22-250.
I originally had it set up to shoot 6 inches over and adjusted it up to about 4 inches with no difference. I check the lenses and try the screens

 

[Anonymous]

I think Chuck pretty much summed it up. Back it off a few feet, tape your rods at 5 inches, and Chuck's tip about placing tape over the sensors works. The Chronys are picky,,,but once you figure out what yours likes, it'll work just fine.