Chronograph snafu

[DrCaveman]

Sunny day today, i was speed testing a hot 38 special load i have been working up. Chrono was working fine without sun screens, confirmed by shooting some baseline rounds with loads i had tested previously

Tested it through my 2 different 357 mag guns, worked great.

Had a buddy with me who has just started reloading, using a friend's setup (he lives a few hours away). He wanted to test his loads through his gun, and they had followed some lee book data with hs-6 under a 125 gr jhp bullet...mid-range 38 spl, according to him. Shooting the loads suggested that his description was about right. His gun: ruger gp100 4" barrel stainless full underlug. Damn fine gun, if i may say

So..... We couldnt get a single round fired from his gun to register on the chrony (shooting chrony f1) after about 12 shots. I got a few "err 1" and a few "err 2", but mostly blank stares from the readout. We installed the sun screens, i balanced a large piece of cardboard over the top of the two sunscreens to shade out the entire chrono...no difference.

I picked up my gp100 stainless 6" barrel, had four out of four read perfectly over the chrono, same loads. Went back and tried his 4" gp100 again.....same results...NO results....

Any ideas what is going on here? I can provide a little more info if needed

[Old Scribe]

Could it be that his boolits were shinier than yours were? A shiny boolit can be the cause. Try putting a black mark with a felt tip marker on the nose of the bullet. I've tried this once and it took care of the problem.

[Reloader06]

How far away from the muzzle were the screens? In my experience, HS-6 is "flashy".

[DrCaveman]

Old scribe: i thought for sure that was the reason, especially after i blasted some of my cast 45 acp loads over the chrony to make sure it was "still working" after experiencing the problems with my buddy's reloads

Alas, no. I shot HIS RELOADS from my gp100 and they registered fine. Out of his gun they would not.

Reloader6: maybe something to this observation. I probably got a fuller burn from my longer barrel than from his 4 incher. Interesting thing is that my "hot 38 special" loads mentioned above clocked the same from both our guns, suggesting that his has a bit less cylinder gap or tighter bore

Interesting situation...thanks for the responses, keep em coming!

[tsubaki]

I have reduced "error strings" by maintaining a few regiments.
Not only making sure the chronograph is level but leveled and square with the shooting rest or position and target. There are only a few inches of elevation usable for the instrument to read. My instructions state "to obtain the best results the projectile must pass 4" to 6" over the eyes".
On sunny to partly cloudy days the diffusers are used. Contrast is key for the eyes to read the bullet. "Painting the bullet" is actually a suggestion in the instruction manual.
Use of a second tripod with an 18" x 24" sheet of corrugated plastic sign material attached to it. Set along side of the chronograph preventing the sun shining at an angle on the sensors, this helps a lot.

[ioon44]

I have had the same issue with my chrono and .357 mag which has a lot of cylinder and muzzle blast .

All of the above is good advice, also I would add keep the box away from the revolver, I even put sand bags around the chrono to protect from cylinder blast.

Also the cords lying on the ground, lay some carpet over them.

[smoked turkey]

I'd say the increased muzzle blast from the shorter barrel was tripping the "start" and "stop" at the shot and causing the errors. I ran into that with my Pact unit. I called them and was told to read the instructions (in a nice way). Sure enough. It is a pain for me but I now place the unit off the bench an built a little insulated box for the sides and top of the brain and no more problems. So I would try moving the unit away from the muzzle blast area and see if that helps.

[Cherokee]

muzzle blast, screens should be 12 ft from the muzzle. Also, his gun might be shooting higher that the 4-6".

[44man]

I have had problems too and made diffusers, light is the most problems and flash from the muzzles. BP is a pain, it will read smoke. Really funny to get 10 fps!
Need to put the screens out farther and get boolits closer to the pickups. They read the shadow of the boolit as it blocks light.
I hate to set them up.

[montana_charlie]

So..... We couldnt get a single round fired from his gun to register on the chrony (shooting chrony f1) after about 12 shots.

The eye of the chrony is trying to detect a dark object passing through a lighted area.
Were his bullets real shiny? Sometimes too much shine keeps the chrony from seeing 'the shadow' it is looking for ... especially on very bright days.

We installed the sun screens, i balanced a large piece of cardboard over the top of the two sunscreens to shade out the entire chrono...no difference.

I picked up my gp100 stainless 6" barrel, had four out of four read perfectly over the chrono, same loads. Went back and tried his 4" gp100 again.....same results...NO results....

Any ideas what is going on here? I can provide a little more info if needed

Yeah.
The cardboard cancelled out the background that 'the shadow' was supposed to be superimposed on.
When there is no light, there is no shadow.

I have a kit for using a chrony indoors. Instead of screens, the rods are used to support electric lights.
If there is no light, there is no shadow.


On a bright sunny day a chrony might have trouble detecting the bullet because too much glare makes 'the shadow' indistinct.
The 'screens' are there to provide a non-glare background for 'the shadow' to contrast with.
A cloudy sky is much like a screen in that it contrasts well with 'the shadow'.

If you want to cover the entire chrony, use something translucent ... not opaque.

CM

[DrCaveman]

Excellent, thanks for the responses. I think we are getting somewhere

Let me throw in a couple more tidbits i didnt mention:

1. Chrono was running great w/o diffusers (ive been calling them sunscreens) prior to shooting my buddy's loads through my buddy's gun, shots were coming from my 4" barrel 357 mag and also my 6" barrel 357 mag, using my homebrew cast loads

2. I left the cardboard "shade" over top of the whole chrony for trying my buddys loads through my 6" gp100, after failing with his 4" gp100... Every shot registered perfectly

3. His 4" gp100 worked fine over the chrony with MY homebrew cast boolit loads, registered fine every shot

4. Out of the 12 shots we fired of HIS loads through HIS gun, two of them showed "err 2" and one showed "err 1". The rest did not even inspire the chrono to display anything

So....
-the opaque shading device theory seems to be dispelled by my success with the same rounds through other guns
-the shiny bullet theory seems to be dispelled by my success with the same rounds through other guns
-the muzzle blast theory *may* be dispelled by the fact that his gun registered fine with my cast boolit loads.

What i didnt try was his jacked bullet loads through my 4" gun. It may have been telling, with the high muzzle blast of hs-6 powder.

Any new thoughts based on this new info?

The whole experience just struck us both as very odd, especially after the immediate success finding chrono readings with my gun and his load, all other variables the same.

Thanks for your patience here, please let me know if i am not being clear about any aspect of the situation

[11B-101ABN]

Most of the problems I have had with a chrony are caused by SUB-sonic boolits. Is it possible that the difference between the 6" weapon mv and the 4" weapon mv, using the same ammo, could put some shots above and some below the speed of sound causing the error codes in the chrony? If the chrony reads the shadow of the boolit as it blocks light, it would seem to me that the boolit COLOR, or SHINE should not matter.

[DrCaveman]

Here's another thing: my 38 spl loads ran the SAME SPEED through both our gp100s, even though mine has 2" longer barrel. They were 180 grain boolits a good dose of 2400, going around 1000 fps (yeah they were "357 only" loads).

His lighter hs-6 loads should have clocked around 850 fps, based on his loading manuals... And they did, through my 6" gp100. No data from his 4" barrel

[Bullwolf]

I've had similar problems with my My F1 Shooting Chrony.

http://castboolits.gunloads.com/show...ting-Chrony-F1

Mine will occasionally return errors, only with my hand loads while reading factory rounds just fine.

This would happen in direct sunlight, indirect, and even angled sunlight. I tried moving back a ways, as well as moving closer, and changing the battery. I even took a black permanent marker and colored a few of my boolits - but I still got the errors.

I got sick of these lighting hassles, and purchased a pair of battery operated magnetic LED lights from Amazon.



Then I placed the Shooting Chrony under the shade of a tree, and mounted the lights on the screens pointing down at the sensors.


Note: The -09- in the picture is the flash reading as shot #9 in my string, I forgot, yet again that the chronograph tries to read the "flash" as a shot, which eventually registers as another error (a user error in this case).

My Shooting Chrony read every single one of my hand loads after adding the LED lights. No more freaking errors! I no longer have to rely on the perfect angle, or quantity of sunlight to read my velocities.

Here's a rare pic of my F1 Shooting Chrony actually working, and checking velocity of a variety of different factory ammunition (22LR, 38, 357Mag, 44Mag) without lights.

Note: In this picture I did not use my camera's flash, so I was able to record an image of the velocity.

If I had been at a public range when all of this was happening, it would have been incredibly frustrating and likely resulted in a wasted trip. As it was I had to re-make my test loads and start over. Now I always bring the LED lights along with the chronograph in case it decides to act up. The lights also fit inside the F1 Shooting Chrony when it's folded up, making em easy to store - and more difficult to leave at home.


Hope this information helps someone else with a fussy F1 Shooting Chrony.




- Bullwolf

[44man]

Another thing strikes me. Maybe he is letting his shorter gun climb more from recoil due to the slower shots with a tad more barrel time. Boolits going too high over the screens.

[mongoose33]

Only slight off-tangent, but let me offer THE best tip I've ever read on the internet: replace the steel diffuser rods with wooden dowels.

If you or someone else should shoot a steel rod, it'll likely take out the chronograph and that's that. Shoot a wooden rod and it just snaps.

The home store sells 'em cheap.

*******************************

I have no idea as to how to answer the OP's question, but Bullwolf, I love that LED light solution; I presume it works just as well at an indoor range?

[DrCaveman]

Excellent tip bullwolf. I will most certainly give that a try and get back to you guys.

44man- that sure is a possibility. Im terribly afraid about shooting the brain...but i could try aiming a little lower

Mongoose: ive already winged the metal rods on several occasions, i even managed to send one of the diffusers off into never never land. I shoot from closer now, like 10-12 feet (*note: i was shooting at around 25 yds that day, to try to get a damn reading from my 44 mag. I should have tried the led thing sooner!)

Thanks everybody

[country gent]

The sky screens can be sensitive to light ( angles, intesity, brightness). Light angkes may not allow the sky screens to "see" the bullets pass over. Bullets being bright or shiny may not give the correct reflection needed. One I have also found is smoke, lube mists unburnt powder granuales wads or paper patches may be picked up and cause an error reading at times. err1 I believe is sky screeen picking up first sensor and not second err2 is the opposite. A wad or unburnt powder that goes thru first screen and picked up before bullet gets to second screen shows as to over first screen and chrono cant decipher whats going on. You see these issues more with the Blacp Powder cartridges where there is a heavy wad, large amounts of smoke, larger amounts of grease ( bullet lube). ANy thing that trips a single sensor and not the second reads an error. It can be interesting sorting problems out at times. Sometimes a few feet one way or the ther makes a big diffrence. Some times a full difusser covering helps. We used to make them from plexiglass and lightly sand blast the surface to break up light. Another is a gaurd in front of the svreens slightly higher to help block wads smoke and debriss that may be there.

[montana_charlie]

Any new thoughts based on this new info?

Nope. Looks like you have everything figured out down to a 'T'.

CM

[Reloader06]

I think(dangerous) 44MAN has it dead on in post 15. I would aim just a little bit lower to get the bullets closer to the "eyes". Be very careful not to go to low, a sure F1 killer.