Shooting chronograph

[raghav]

I want to find FPS of my air pistol.

Where can a shooting chronograph be bought in Calcutta ?

Will be glad for whatever details anyone can provide.

[nagarifle]

put a post in the wanted section. they are hard to find

[adkol]

They are not available in Calcutta.

[rishudhawan]

easy to make a crude one at home, you need a computer with mile and a metal back stop, and a programme from the internet(i forgot the name). Basically the setup records the time you press the trigger, and the time the pellet strikes the backstop, calculates the time difference, and factoring in the time taken and distance gives u the fps.

[to_saptarshi]

Chronograph is not a prohibited item , if possible try importing one.

easy to make a crude one at home, you need a computer with mile and a metal back stop, and a programme from the internet(i forgot the name). Basically the setup records the time you press the trigger, and the time the pellet strikes the backstop, calculates the time difference, and factoring in the time taken and distance gives u the fps.

Very interesting . How the software will get the exact timing of trigger release and pellet hit ? There should be a sensor to record that . Are they using a microphone to record the sound ?

[t20]

Most easy to make one could be ballistic pendulum. It will give you decent result.
And if you love to play with electronics, go for using photo diode.

Capturing with microphone could be more error prone.. DO NOT TRY you will waste your time

[rishudhawan]

Yes using a microphone to capture the sound when the shot id fired and then again when the pellet strikes the metal backstop.

No cost and very easy to make.

Another method is using what is called the poor mans crony...essentially an empty aerated soft drink can, if the pellet pierces then it is about 330fps.

++++++++++++++++++++++++
Very interesting . How the software will get the exact timing of trigger release and pellet hit ? There should be a sensor to record that . Are they using a microphone to record the sound ?[/quote]

[raghav]

Thanks folks for the feedback(s).

@t20
What is a ballistic pendulum , could you explain a bit ?

@rishudhawan
I have already downloaded a freeware software chronograph from the internet , now on the lookout
for something that will start & stop ( i.e toggle) the stopwatch on input from mic/soundcard. Any suggestions ?

Re the empty aerated soft drink can , ( i ) from about how far should the can be shot with .22 mastershot pointed export quality ? ( ii ) 330 FPS is when the pellet pierces the front OR when/if it comes out thru the other side ?

[dev]

You can import a chrony from England for less headache. Get a combro chrony, you can check it online and then buy it with a credit card from their site. It is pretty handy, just make sure that you use a rod to center the chrony to the rifle barrel.

Regards,

Dev

[raghav]

Apparently someone has already done a DIY sound actuated software chronograph.

It seems it is off by only 5 - 8 FPS as compared to a commercial chronograph ... !

@rishudhawan : The program is called softChrono. Thanks for pointing me to it .

The download link is here :-
http://talonairgun.com/softchrono/SoftChrono_beta1.ZIP

The program is written in VisualBasic and may require a DLL or two to be downloaded / installed. The ini file needs to be populated with the DISTANCE , PELLET WEIGHT etc and it will do the calculation to derive pellet velocity using these stored parameters and the time interval between the audio cues of trigger pull and pellet hitting the target.

Going to check out the program on Monday when I return to BBSR.

[to_saptarshi]

Capturing with microphone could be more error prone.. DO NOT TRY you will waste your time

Where you got this info ? Could you please explain ????

Worlds Most recognised Simulators like SCATT are used small microphone to recognise the trigger click to determine exact timing of when the shot was fired, and I have never heard anyone complaining that their process is error prone or errornious.

[t20]

My friend, are you not confused between ballistic measurement and simulation?

Tell me, which one more accurate (all are in Milli seconds)?
Scenario1(Sound): Recording started. trigger pulled-1st stage-2nd stage-hammer hitting/piston leave--blast occurred/pellet started moving forward in barrel --hits the object (record stop) Not sure which pointer to hitting object you will take.

Scenario2(Photo diode): Record starts after pellets/bullets leaves from the barrel

May be you can tell me how many you know professionally using sound to measure ballistics

[raghav]

Well I've been able to set up softChrono at last ( after plenty of inconsistent / improbable results )
and now it gives me relatively consistent readings.

Minimum FPS reading : 233
Maximum FPS reading : 261

No. of shots : 18

The following factors are important :
(1) Distance between the muzzle & target - greater the better - 28 feet in my case.
(2) Placement of the laptop / microphone - exactly midway between the muzzle & target.
(3) Adjustment of recording volume of the mic.
(4) Nature / accoustic property of backstop - metal / wood / other. Mine is a big metal platter !
(5) Softchrono parameters - muzzle volume & impact volume. This seems to make a lot of difference. Mine are
set to 30 & 60 respectively.

To sum up , while it is not the last word in accuracy , the Laptop / Softchrono setup when calibrated properly
does give an approximate idea about pellet velocity , based on which I am able to arrive at an average
pellet velocity of 247 FPS for my Commander Mark III air pistol ( .22 ). This is after the pistol has gone through 700 shots.

[OverUnderPump]

Ditto to what Dev said,import one from Combro Chronoscopes, it will spare you the headaches. The guy at Combro is a gem to work with, I have spoken to him several times. That said, if you have a fetish for headaches, then you might as well go ahead and make one .

regards

OUP

[rishudhawan]

great going raghav... that's the spirit... the pleasure in seeing something built ourselves is indescribable.

now if one wants very exact fps readings then a brander chrony may be useful, but your setup seems more than enough for most of us.

rishu