chrony heads-up

[murf]

was out for a shooting session with my 357mag and 44spl blackhawks this afternoon. while shooting over my Shooting Chrony (beta model), i got two strange readings (see attachments).

strange, but almost identical. what i figure is the two pulled shots went over the edge of the photo cell, instead of the middle. the shots were under the sky screens and above the body of the crony.

just an fyi. the numbers are too close to not be significant. the entire session was shot from the same position of the shooter (me), the chrony and the target. nothing changed but the new target on the frame (both in the same place on the frame).

murf

 

[gamestalker]

Ya, I have that same chrony and if I don't keep them going in the general center line of the photo cell, I get some screwy readings. Another thing that will cause weird readings is if I'm too close to the chrony. I think when I'm too close, it will read gases and sound waves. But over all and considering the physics of chrony's, most fps readings are pretty reliable.
GS

 

[Walkalong]

Things happen. I was getting so many strange numbers one afternoon I just chalked it up to the sun angle and scrapped all the numbers. The next day everything was normal.

I see they are midrange loads. Did you tip the barrel up before every shot? Did you drop the barrel for those two low velocity readings perhaps?

 

[murf]

walkalong,

not that i recall. the process was the same for all rounds fired. shoot, record the velocity, walk to the target and mark the shot, walk back and repeat. the only variation was when reloading after the sixth shot.

murf

 

[1SOW]

Two weeks ago, I was chronoing a new 9mm load and all was going great. I fired a few more and the speed went up "300 FPS", say what??

The sun was beginning to come over the edge of the roof I was under. One sensor in the sun, one in the shade. I had the sky screens on but made no difference.. 300 FPS, wowee.

I moved the chrono closer and out of the sun, and all was normal again.

 

[kingmt]

I spent a few hours trying to figure out why mine wouldn't work one day. I went & turned off the fencer & all was well.

 

[murf]

yes, they are temperamental. i think 12 feet away is too much. maybe 6 feet away next time. that, or lower the chrony a bit more.

guys, how far away is your chrony when you shoot?

murf

 

[Samari Jack]

I've a couple of suggestions I've learned through trial and error. I put some electrical tape on the aluminum arms to give a spot to shoot between. Mine is one of those cheap $80.00 wonders that must be interpreted with a grain of salt but generally over 10 shots or so gives me a reasonable idea of where the reloads are. I typically throw out the high and the low, then average the remaining eight. I use 8 ft distance. I put clear strapping tape over the eyes to keep burnt powder and debris off the eyes, cleaning the tape with a damp cloth occasionally. It is a pain to read but to keep from shooting the thing I nailed together six 2x8s positioned in front of the first eye to catch a wild shot. I haven't shot the wood yet but feel a lot better with my cheap chrony somewhat protected. Probably wouldn't work with a long gun, or at least 2x8s.

 

[Lost Sheep]

I've a couple of suggestions I've learned through trial and error. I put some electrical tape on the aluminum arms to give a spot to shoot between. Mine is one of those cheap $80.00 wonders that must be interpreted with a grain of salt but generally over 10 shots or so gives me a reasonable idea of where the reloads are. I typically throw out the high and the low, then average the remaining eight. I use 8 ft distance. I put clear strapping tape over the eyes to keep burnt powder and debris off the eyes, cleaning the tape with a damp cloth occasionally. It is a pain to read but to keep from shooting the thing I nailed together six 2x8s positioned in front of the first eye to catch a wild shot. I haven't shot the wood yet but feel a lot better with my cheap chrony somewhat protected. Probably wouldn't work with a long gun, or at least 2x8s.

Have you tried shooting the 2x8s without the Chronograph behind them to see how they will behave?

My Chrony wears channel iron (my shooting buddy has a 500 S&W). A shallow hit from Buffalo Bore 350 grain barely leaves a skid mark.

Wise decision to have protection.

Many people use wooden dowels instead of the metal support rods. The wood will break if hit and not drag the instrument with it. The metal rods tend to knock everything. over.

The clear tape over the sensors is a good idea. I may try it this summer. However, if you are getting soot on your sensors I think you may be too close.

Good luck

Lost Sheep

 

[41 Mag]

With my Chrony's, I try and be consistent and set it up at 12' for just about everything. I do have a couple of magnum rifles that require it be set further out due to muzzle blast, but those are the minority of my shooting. I have one of the old red versions and also one of the newer Master models.

I have found that using tape, or the brass couplers on the rods, to be fine spots to set up for, and usually give the same reading from one secession to the next.

Sun, shade, clouds, will all effect the readings depending on how bright it is around the sensors. When, or if, I am getting errant readings from a known load, I usually take a spare target and use a couple of clothes pins to attach it to the screens long ways. This will put additional shade on the sensors, but also give a more consistent background for them to pick up from.

I have set mine up, one up close and one at the target for both my firearms, and my bow, just to check both starting and downrange velocities. This is however only done once I have everything tuned and dialed in properly. So far in over 15 years I have not managed to put anything through either one of the two I have. Knock on wood.

 

[sourdough44]

I was using mine the other week & had some bad numbers. This was about the 1st time ever. My usually spot to set it up was bright sunshine. A few days later under mid-level clouds all was well again.

 

[murf]

went out shooting again, yesterday. sunshine all day and this time i lowered the chrony a bit and shot higher up toward the screens. kept it at the same 12 feet out, though.

no bad numbers this time, although i only shot ten times.

go figure!

murf

 

[Lost Sheep]

More sensitive Chronograph - more sensitive to light variations

I was using mine the other week & had some bad numbers. This was about the 1st time ever. My usually spot to set it up was bright sunshine. A few days later under mid-level clouds all was well again.

Yep. Under bright sunshine, your Chronograph is trying to read the shadow of the bullet being cast by the light coming from the clear sky. Clear sky has very little light to cast that shadow. If there were no atmospheric scattering (haze, clouds, your Chrony's diffuser screeens, etc) the sky above the sensors would be the dark of outer space and you would get nothing at all.

It is an even worse situation if one end of the Chrony is in sunlight and the other is in shadow and forget about it if you have windy and partly cloudy conditions where the cloud shadows are passing every 15 seconds.

This applies pretty much to all light-based chronographs. The electrical contact ones are immune (but have their own shortcomings) The infra-red ones are supposed to be immune as well, but I have no experience with them.

Lost Sheep