First time testing with my chronograph

[WrongHanded]

And it didn't go great.

Sunny, windy, I probably shouldn't have tried. (73 degrees btw)

So what happened?

It started well, with 3 rounds of leftover .45 acp. SNS coated LRN 230gr. They went at mid to low 800's. Okay.

Then some Double Tap 230gr FMJ-FP, which they advertise as 1,000fps from a 5" 1911. 10 shots:

1,216
195
1,222
205
917
1,230
923
1,225

Not right at all. But I persisted with another handload. 11 rounds of a 230gr RNFP over 5.6gr of W231. These averaged 854fps, except for the 1,190 and 1,236 results.

And still I continued. As I'd paid for the range time and driven a good distance.

Out of my BH 4-5/8 .41 mag, a 210gr XTP over 15.5gr 2400. Mostly in the 1200's, with a couple at slingshot velocities, and the only reasonable result of 1,064. Not a good sign.

And then with the same gun, a 230gr WFN with 17.0gr 2400. I could almost believe this would run in the low 1200's (which is mostly the results I got) but the other numbers make me second guess that. And then there was the 915fps and 1170fps readings. I'd been very careful with my powder charge weights on this particular load.

My RH .44 mag with 5.5" barrel, gave me from 1,066 to 1,241 shooting a 240gr XTP over 9.0gr of W231. And that's where I stopped to think.

Perhaps I had the chronograph too close. Is was maybe not quite 10 feet away. So I moved it to 15 feet or so. I though perhaps I was getting false reading from the muzzle blast? How could I know if I didn't try. But that didn't seem to help.

I tried 20 rounds at both 11.0gr and 11.5gr of Unique under a .44 mag 240gr LSWC. Now these numbers may be higher than the Lyman manual I have, but barring some readings in the high 1500's and low 1600's, I think they could be accurate.

11.0gr Unique, 240gr LSWC, .44 mag 5.5" barrel. 10 shots:
Average - 1,196
Low - 1,161
High - 1,211
E.S. - 50
S.D. - 41.82

11.5gr, 7 shots
Average - 1,234
Low - 1,219
High - 1,256
E S. - 37
S.D. - 11.487

Except that the other 3 shots were:
1,640
1,576
1,689

I got more strange numbers from the same .44 mag. This time shooting a 300gr 'Hammer' from MBC over 16.5gr 2400. Where I got some 1200's, some mid 1,000's, and some 200's.

I also tried some 310gr Montana Bullet Works LBT WFN-GC at 17.0gr 2400. Also some wild numbers. As high as 1,206 and low as 535.

Doesn't all this make me sound like I have no idea how to reload?!

And THEN, I tilted the tripod so the sun didn't hit the sensors! I put it over at about 45 degrees, to where the sensor windows were casting a shadow over the sensors. And NOW I start getting consistent numbers.

The 300gr Hammer with 16.5gr 2400, 10 shots:
Average - 1,076
Low - 1,043
High - 1,114
E.S. - 71
S.D. - 22.24

And lastly, I shot 20 rounds of that 310gr LBT WFN-GC, with my preferred 16.8gr 2400, from the same 5.5" RH in .44 mag:

Average - 1,112
Low - 1,087
High - 1,149
E.S. - 62
S.D. - 16.6

So I don't know if wind gusts moving the chrono are a likely cause of some of the very low or very high numbers, but I think the sun hitting the sensors definitely had a negative effect on the readings. Unfortunately, that .41 mag 230gr WFN load is one that I really wanted to get velocities on, as it seems to be amongst the most accurate load I've worked up.

Anyway, I learned some valuable lessons about what not to do with a chronograph. The unit is a ProChrono Digital from Competition Electronics, if anyone wants to know.

 

[drband]

Were you using the screens?

 

[WrongHanded]

Were you using the screens?

I sure was. I even read the manual.

 

[LoonWulf]

Sun angle? Fresh battery? Chronograph square to the firearm? Shots fired over the same point each time?

That's my usual checklist when working with an eyeball Chrono. Even changes in cloud cover can affect them. Sun angle is the next most common issue I've had.

Good work figuring out how to get it reading, they are an important, if finiky tool for the reloaded.

 

[rfwobbly]

Screens or not, my guess is you're having issues with the light. Try early morning, or late in the PM when the light is more diffused. If you really need to work in the middle of the day, then you need a big sheet of white cloth or white plastic to stretch over the 4 dowels. Or even one of those 10ft square picnic tents.

 

[lordpaxman]

RTFM?
Read page 3 again:
“Make sure the sensors have a clear view of the sky but the chronograph itself is within the shadow.”
Good thing you figured it out! There’s a reason the chrono stage at a match is under a tent and the chrono’s are in a box with the lighting package added on. Unless you visit the Battle of Saratoga where they have 3 Labradar’s!
I had the best luck with a slight even overcast diffused light days. Or, the sky screens evenly lit but the unit in shadow. Remember even a difference in angle over the sensors will alter the path length and therefore the calculated speed.
Certain shiny projectiles are hard to chrono as well, so take a black sharpie. A good solid tripod or stand is necessary as well. Oh, and, try not to shoot the darn thing, or build a boo-boo plate!
I’d also suggest you purchase some factory ammo to shoot, record it, and then keep that box as a calibration/checking ammo to use as the first string for any session just to assure yourself it’s reading close.

 

[Legionnaire]

Others have said it. Sun. The unit needs to be in shadow. I went through the same learning experience years ago. Couldn't figure out how my .44 magnum revolver with light loads was doing upwards of 2,000 fps. One of the bays at our range has a car port roof built for the purpose. I used that from then on ... until I got a Labradar.

 

[alfsauve]

Ah the joys of an optical chrono. Paid my dues for years with a Chrony brand. Posted similar question one time and to my surprise Mr. Oehler gave me tips on what was wrong. I ended up using a large piece of Roscoe white diffusion gel in a home made frame to get the sensors out of the direct sunlight. Either that or wait for an overcast day.

How much simpler life is with a LabRadar.

 

[Bfh_auto]

I sure was. I even read the manual.

Cheapest fix is duct tape and a target taped to the sky screens. Most work good is a pop-up awning.
I suggest anchoring your tripod either with tent stakes, or a weight. Mine died from blowing over one too many times.

 

[Blue68f100]

I thing the best fix is when you mount the crony up side down so they are always in the shade. Then you don't need to use the screens at all.

 

[Legionnaire]

I thing the best fix is when you mount the crony up side down so they are always in the shade. Then you don't need to use the screens at all.

Why did I never think of this? I still have an optical chrony and will have to give it a try. I imagine the most challenging thing is rigging up an upside down mount.

 

[alfsauve]

I thing the best fix is when you mount the crony up side down so they are always in the shade. Then you don't need to use the screens at all.

Wow. I guess you lay white poster board on the ground below it to get more light if neede. Sometimes I feel so dumb not thing about something like this

 

[WrongHanded]

Similar conditions today, except I was in the foothills and not the plains. So a little more shelter from the wind, and some good shade from trees (the manual says not to use trees, but... I did).

I was able to test the. 41 mag loads I couldn't get good readings on yesterday. And then I shot at rocks about 175yds up a hill which was possibly the most fun I've ever had whilst shooting. I can't believe it's taken me this long to try longer distances with a revolver. A good day!

 

[Dudedog]

First time testing with my Chronograph
And it didn't go great.

Whew, I was worried you were going to say you shot it!

Glad you got it figured out and got some good numbers.

I even read the manual

It's ok to read it, even a good idea, just never admit you did

Most of the time if you get funny numbers it's lighting, bad/weak battery or muzzle blast.

I have ProChrono as well and most of the time it's not to picky about lighting but lighting can be an issue.

 

[Dudedog]

BTW if you do shoot it I think Competition Electronics will repair/replace it for 1/2 the price of a one.

I haven't shot mine (yet) to find out if they will or not.

Be careful testing scoped rifles, up close line of sight thru the scope and line of bullet flight are off enough to cause issues.

Lot's of chronos have died from lead poisoning, makes me wonder if that is their most common failure mode

 

[LoonWulf]

Ya know, I've shot thru my eyeball Chrono at 100yds with my magspeed on my barrel and haven't shot it yet.......
Plan on doing it again next range trip actually.... It's really hard to set up by yourself.

 

[lordpaxman]

It's really hard to set up by yourself.

Even at 5 yards it’s a few trips to try to get the trajectory even across the sensors. If you put a target directly behind the sky screens it at least gives you a better chance to aim and possibly miss the chrono. Watch the offset of certain black rifles, remember they’re shooting low at 5 yards, don’t ask how I know. The boo-boo plate saved the plastic.
Replace the steel rods with wooden dowels and you’ll transfer less energy to the electronics if you hit them.
And as others have pointed out, Labradar’s or magspeeds avoid some of this.

 

[drband]

Replace the steel rods with wooden dowels and you’ll transfer less energy to the electronics if you hit them.

This is a true statement!

 

[alfsauve]

Replace the steel rods with wooden dowels and you’ll transfer less energy to the electronics if you hit them.

Oh great. NOW you tell me.

 

[Old Stumpy]

Replace the steel rods with wooden dowels and you’ll transfer less energy to the electronics if you hit them.

I did this. I even made my own flexible diffusers with larger dowel segments, thin plastic sheet, and wood screws.
Much better.
Slipped one day and drilled the rear sensor and the case.
Sigh.....