[YABA]

I just bought a Shooting Chrony F1 Master. Ive found that it will occasionally give verry erratic readings. On a 10 sting of 9mm 147 gr 8 of the shots were within about 30fps of each other at the 900 fps mark, I had one shot up at 2700 fps and another 1 below 700fps. Ive shot a couple other strings with similiar erratic readings.

Ive got a hard time beliveing that I had a 9mm going that fast without excessive recoil or damage to the pistol. Could this possible be the way Ive got it set up or is the Chrony pehaps having issues?

Ive got the Chrony about 10' from the gun.

[yoshidaex]

possible lighting issues.
try setting up in the shade.
you'll get different readings thru out the day due to the location of the sun.
can't recall if you start getting faster or slower readings when the sun is at its peak.

[G-ManBart]

YABA, on Aug 4 2009, 09:12 PM, said:

I just bought a Shooting Chrony F1 Master. Ive found that it will occasionally give verry erratic readings. On a 10 sting of 9mm 147 gr 8 of the shots were within about 30fps of each other at the 900 fps mark, I had one shot up at 2700 fps and another 1 below 700fps. Ive shot a couple other strings with similiar erratic readings.

Ive got a hard time beliveing that I had a 9mm going that fast without excessive recoil or damage to the pistol. Could this possible be the way Ive got it set up or is the Chrony pehaps having issues?

Ive got the Chrony about 10' from the gun.

Lighting can do it, but so can muzzle debris getting thrown forward. I'd back off a couple of feet just to be sure. I normally use 15ft. Oh, and small bugs that fly by at just the right (wrong) time can mess with your readings as well....had that happen once and noticed a cloud of gnats near the chrono. If possible, try to set the chrono in the shade and keep direct light off the sensors....you may have to tape a cardboard target or something similar up on the side of the skyscreen supports to help with this. Overcast days are the best for good readings. When I get around to it I'm going to build a light box to put the whole chrono in just to avoid problems with lighting. R,

[LPatterson]

My F1 Chrony gave different readings depending on height over the sensor, I finally created a window out a piece of cardboard that started ~ 4" above the sensor with a 4" opening and tried to aways shoot through the hole. One day I put it out of my misery (I used it for target practice) and bought a CED.

[Jman]

YABA, on Aug 4 2009, 08:12 PM, said:

Ive got the Chrony about 10' from the gun.

Make it 12'

Set it in the shade. (no direct sunlight)

Should be fine.

[gm iprod]

Verify the unit is functioning with a 22lr rifle and T22 for example. And try all the above tips.

[Service Desk]

Chronographs seem to be a law unto themselves.... I have 2 PACT MkIII units that are always within 10 fps of each other for most shots.. then one will just freak out and throw strange readings while the other is OK. All the remedies detailed in this thread will fix a problem, but you have to know which one !

Muzzle blast and concussion will trigger some chrono's so 10ft from muzzle to screens is a minimum, good filtered light is necessary for most units, I used to put a piece of opaque drafting film over my pact screens to keep the light constant, now I am lazy and use the plastic bag from inside a Cheerio's box. It works just a good and is easier to find.
Another trick is to use a battery pack of 6 AA cells instead of a single 9v battery - the power supply for the screens is drawn from the same 9v battery that drives the electronics in the PACT, so a used battery can influence the reliability - relative to a new one.

To overcome this problem I use a 6 Alkaline AA cell battery pack (9 volts) or an 8 cell rechargeable AA NIMh battery pack for 9.6 volts on the PACTs, no problems and normally very consistent performance, especially for extended chrono sessions.
I have found that most Chrony's also perform more reliably (for longer) with a battery pack rather than a single 9v battery.
Lead projectiles seem to be easier for the screens to see on bright days and jacketed ones are harder to see, so keep a black marks-a-lot or similar and give jacketed projectiles a quick blackening to improve the chrono performance.

The other essential tool is a sense of humour... 'cause sometimes the damn things just don't want to play the game.

[alellis]

[quote name='G-ManBart' post='1031395' date='Aug 4 2009, 10:22 PM']

When I get around to it I said:

I also plan to build a chrono box.

I am wondering how much light is needed. ?
<

I also plan to build a chrono box.

I am wondering how much light is needed. ?

al

[uscbigdawg]

I'll add to the debris/blast group. I had the same problem with some rifle load readings and that was the problem from a VERY reliable chrono, lighting be damned.

Rich