Prochrono Digital question

[preacherJohn]

I was checking the speed of some light 40 loads this aftn shooting at some steel 25yrds away. After I recorded what I was looking for, I decided to shoot the 9mm PPQ a little bit and see how hot the HP38 loads were. Everything was pretty normal up until I started to shoot some factory Fed 115's. They were only reading around 565fps average. I probably shot about 20 or so rounds of these Feds and they all were coming in at that. I thought, huh? The box said at muzzle, they should be around 1125fps. I didn't notice that big of a difference in the recoil from the HP38's @ 4.3gr that was averaging around 1101fps or the 4.0gr of HP38 that was around 1040fps. Either way, all of them was hitting the 8" steel target with a few misses. I did have the deflectors on, and was also under my gazebo on the deck shooting out into the yard. I'm stumped on how the chrono was recording the Fed 115's so slow though as compared to the reloads that seemed to be on par. Just for added note, the 40 S&W with 3.9 gr of HP38 were averaging 701fps, and the 40 with the WSF @ 4.4gr were averaging 737 with one round at 655fps. The chrono in question is the Prochrono Digital CEI-3800. The pistols were a Sig P226 40 with a 15lb spring on a SS guide rod, and the Walther PPQ Q5 with standard rod and spring.

 

[LoonWulf]

I think you have a lighting issue, take it out of the gazebo and try again just to be sure.

Most likely you were right on the edge of the units functional vision, and the other bullets were easier to see. Or the light changed just enough to cause an issue for the 9s.
I've found my PCD to be quite accurate when set up the way it wants, in a spot it gets aa goo unobstructed view of the sky.
But it can be a fickle, pain in the butt sometimes.

Wierdness in velocity is usually the first sign it's grumpy about lighting.... generally low like you had.

 

[rfwobbly]

The color of the bullet can cause issues with the unit's ability to "see" it pass over. Also the position of the sun is critical. I have the best luck in subdued light, like on highly overcast days or late afternoons.

 

[preacherJohn]

You know, come to think of it, I've had some pretty weird and slow speeds on some 45acp lead that were reading anywhere from 345 - 465. I wouldn't think that would be fast enough to shoot out of the barrel. I guess it may be the light. I like shooting under the canopy of the gazebo, maybe I'll just remove the deflectors and see what happens. Maybe I'm wrong, but I always thought when the sun was high is when you used the deflectors, so in the shade under the gazebo I thought it would read alright. I guess I'll have to read up some more on it. The reloaded bullets were a nice shiny copper plate, where as the Feds were kinda dull jacketed stuff; you know how they get when their in a bulk box of 100.

 

[rfwobbly]

I never use the defusers on any chrono. Heck I never use the wires... always chopsticks ! My shooting/chrono area is surrounded by mixed trees, and 4-5 o'clock light is bright, without being direct. I get good, reliable readings standing out in the open, about 12-15 ft from the unit.

 

[mcb]

How close where you to the chrono. Just a guess, but I am betting the cheap fast burning powder in the commercial ammo was generating enough smoke to trip the front screen of your chrono. Since the gases are initially moving faster than the bullet it trips the front gate then a bit later the bullet comes along and trips the back gate (the chrono is now ignoring the front gate since its alread sensed something) and you get an artificially low velocity reading. That did not occur with your reloads since they generated less smoke. Just a guess. Any time I have seen artificially low values its either I am too close having a smoke issues or I have a weird shadow on one gate and not the other.

 

[brutus51]

I've had a similar problem only in the opposite direction. Imagine my surprise when my .45 ACP loads were clocking in at 4,000 fps., talk about bragging rights.
Problem was the Extreme plated bullets I was using were so shiny they were giving false readings. painted them with a magic marker and I was right back in the 850fps. range.

 

[Dudedog]

Had to be something funny unless the chrono is going nuts.
If it does it again shoot one more round of something different through it real quick to see if you get a funky reading on it.
If you get a funny reading still it is probably a lighting issue or the chrono going nuts, if you don't then it is probably something like mcb described above.

Only issues I have had with mine are, it behaves funny right before the battery gives out, and it reads strange if I am to close with something that has a lot of muzzle blast, say like a .357 with H110.
(both of which are my fault not the chronos)

 

[Jim Watson]

Never had such a problem with mine.
But I don't have it any more, the rfwobbly technique led me to shoot the box.

 

[Blue68f100]

Sometimes if you are shooting on the edge of the windows you can get strange readings.

 

[Walkalong]

I shot some rounds over mine late this afternoon, the sun was down low when it showed through the clouds. I got one reading that was 200+ FPS off (Low) from the others. Likely just an error due to tough conditions for the chrono. I'll re-test of course, but am not overly worried about it for now. It sounded and felt the same, and went into the small group at 7 yards.

I have not seen the Berrys 83 Gr HBWC in 10 years, and am almost out, so I am testing the MBC 98 Gr coated WC. It shot very well today in the .32 Long and the .32-20. A little smokey, and a little smelly compared to the plated Berrys, but not bad.

If anyone knows where some of the Berrys are, I'd love to hear about it.

 

[preacherJohn]

the gases are initially moving faster than the bullet it trips the front gate

All these replies are good, but this one stood out to me. After a bit of research, I found out that the chrono (according to the manual) for a pistol should be 5-10 feet away. I'm shooting a lot closer to it than that. I never realized that the front eye would pick up the gases first. This does make sense especially for the slow speeds. I also like the "marking the bullets" with a marker idea. Could incorporate that in at the reloading bench when working up loads.

Imagine my surprise when my .45 ACP loads were clocking in at 4,000 fps

This one made me laugh out loud!

Once upon a time, I used to think I was shooting to high over the chrono and raised it up. Then I happened upon a new pistol and was trying it out, I wasn't used to the sights and unaware of where "the hold" should be on the front blade, and it shot lower than what I was used to. I ended up nicking the real of the chrono. Not enough to hurt it, but grazed the rear of it enough to break the plastic house some.

All in all, it has been a few years since I've changed the batteries. I don't use it that much, but I guess the shelf life may be getting weaker.

 

[Walkalong]

After a bit of research, I found out that the chrono (according to the manual) for a pistol should be 5-10 feet away. I'm shooting a lot closer to it than that

I always walk five good paces and set up the chrono, two more and set up the target. So basically 5 and 7 yards or 15 and 21 feet. I do that for rifle or pistol.

9MM Load # 109

 

[mcb]

All these replies are good, but this one stood out to me. After a bit of research, I found out that the chrono (according to the manual) for a pistol should be 5-10 feet away. I'm shooting a lot closer to it than that. I never realized that the front eye would pick up the gases first. This does make sense especially for the slow speeds. I also like the "marking the bullets" with a marker idea. Could incorporate that in at the reloading bench when working up loads.


This one made me laugh out loud!

Once upon a time, I used to think I was shooting to high over the chrono and raised it up. Then I happened upon a new pistol and was trying it out, I wasn't used to the sights and unaware of where "the hold" should be on the front blade, and it shot lower than what I was used to. I ended up nicking the real of the chrono. Not enough to hurt it, but grazed the rear of it enough to break the plastic house some.

All in all, it has been a few years since I've changed the batteries. I don't use it that much, but I guess the shelf life may be getting weaker.

CED and one or two other makers sell sensor shades with IR LEDs in them. The sensor eyes that many chrono manufactures use are actually more sensitive to IR frequencies than visible spectrum. By using the IR illumination the chrono is even more reliable and tolerant to bad lighting conditions and bullet color. If you really want to make a reliable light gate chrono you use IR illumination and put them in a box to eliminate the ambient light and smoke encroachment as much as possible. A chrono box is pretty common setup at big USPSA/IDPA matches.

 

[Dudedog]

Once upon a time, I used to think I was shooting to high over the chrono and raised it up. Then I happened upon a new pistol and was trying it out, I wasn't used to the sights and unaware of where "the hold" should be on the front blade, and it shot lower than what I was used to. I ended up nicking the real of the chrono. Not enough to hurt it, but grazed the rear of it enough to break the plastic house some.

Well no wonder it's not working right you shot it in the a$$.
It's probably not real happy!

If you really want to kill the chrono you must get it in the brain (button area) and drive the bullet deep into it's vitals.
Chronos are thin skinned so it dosen't take much, I have heard a .32 wadcutter will work just fine.
No wounding and suffering allowed here, we need to strive for clean kills.

Don't know if it's true or not but I have heard Competition Electronics will repair/replace them for half price even if they die of lead poisoning.

I would give it a new battery, move it back a bit and try the 115s again.
Please let us know if that makes it happy, curious as to what the cause is, lighting, gas, muzzle blast etc.

Distance wise for all my 9mm stuff 7-10' seems fine.

 

[preacherJohn]

I have heard Competition Electronics will repair/replace them for half price

I read somewhere that someone contacted CE and they told them that it happens all the time and would fix it for $40. That's been a year or so ago, but it is good to know that you don't have to replace the whole thing for one misplaced shot.

Please let us know if that makes it happy, curious as to what the cause is, lighting, gas, muzzle blast etc.

I'll get back to you on the cause; I'm going to be pretty busy for the next week when the weather dries out and cools down, but after that I'll try it out again; maybe sooner if'n I get a break.

 

[Walkalong]

They are not careless proof.

 

[Jim Watson]

Hmm, I'll check that out. I have reverted to my old CED which has more bells and whistles, but is more trouble to set up.

 

[preacherJohn]

Here's a double pic of nicking mine last year. I think it gives it "character."

 

[ray15]

Here's a double pic of nicking mine last year. I think it gives it "character."

If that's character I have one with a fully-formed personality.

 

[Dudedog]

If that's character I have one with a fully-formed personality

Is it still alive?

They say there are 2 kinds of chrono owners, those who have shot their chrono and those who will
(Lab radar and magna speed owners are probably safe here)

 

[ray15]

Is it still alive?

The faceplate looks rather like Walkalong's.

 

[preacherJohn]

OK, I got the chrono back out this aftn to check some light 40 loads and it seemed to work fine. What I didn't do was change the battery or get off the deck (I love shooting on the deck because it's easy to find my brass and it's nice being in the shade), but what I did do was take the deflectors off, and back up about 6' away from chrono. Out of 5 strings of 5 shots, only one looked a little suspect coming in about 75-80fps slower than all the others. That could have been anything as 24 other shots were pretty comparable.

I found out WSF with the 40 S&W was pretty accurate in the 4.4gr range with a 165gr FP copper plated Xtreme bullet. The Sig P226 functioned OK also and the speed out of 3 strings were averaging 749 - 758 - and 745fps. This was with a 15# spring and SS guide rod.

The HP-38 @ 3.9gr wasn't nearly as accurate with same bullet and FTE several times but was averaging around 700fps (much slower). I'm still not done fooling around with this powder in the 40 tho. I might start bringing the charge up a little bit.

Either of these rounds were pleasantly surprising to shoot with minimum recoil. And after seeing the hand doc, he wants me to have a nerve test for wrist issues as of the beginning of this week, the low recoil was much appreciated.

 

[Hondo 60]

I have heard Competition Electronics will repair/replace them for half price

They'll charge UP TO 1/2 of the msrp($60)
But I had mine repaired for $40 something, including shipping.
They don't always charge 1/2 the msrp.
That's only if they can't repair yours.

And I've had times of really weird numbers.
Either way too high, or way too low.

If you're far enough away to discount muzzle flash, then it's lighting
either the sun or lack of sun

 

[Blue68f100]

Those EMG test are very painful. I've had several on my back to confirm what I was feeling in my legs. They do give the neurologist a good mapping of which nerves are being affected. I have something going on with my shoulder and the doctor thinks it may be a disk problem in my neck. I sure hope not.

So did you have different lighting conditions when you ran the crony this time? I have the most problem late in the evenings. Since I now shoot every thing at 15', I have less issues. It also depends on weather I have a break on a gun or not.