Got my Chrony

[Basu]

Dear benne,
Pleased to see that you have taken time out from your family and did the trial.
I understand that it is difficult for chronoconnect to capture proper sound amidst echos.I like to still compare the sound sample in audacity.
My SDB45 returns 185-193 meters per second in chronoconnect with same 11.6 grns pellet.
Hope it is not a very bad reading either.

Basu

[Big Daddy]

Hi bennedose, I can imagine the heart stopping moment when you hit your chrony. Congratulations on your gadget.

BD

[sumanngon]

So very buying one!!!

[xl_target]

It is more than adequate and for the price is a good value. I've shot my skyscreen rods many times and have had to make substitute rods but it still keeps working. Luckily I haven't shot the Chrony itself. It just takes a moments inattention and poof, there goes a hundred bucks.

Words from the wise indeed! I think almost everyone who has owned/ owns a chrono probably has shot it/ or some part of it - some time or the other! Of course if the rifle is any type of centrefire rifle, you can usually bid adieu to your chronograph!

Cheers!
Abhijeet

Oh by the way - I successfully shot my Chrony and dented a bit of metal - but it's still working.

You're correct Abhijit, I think every Chrono owner has shot some part of it.
If you shoot enough, you will shoot the sucker. I think Baljit shot two of them.

[bennedose]

LOL! Easy for me to laugh now - but I got the shock of my life when I did it!

Actually the instruction book specifically warns against the mistake I made - it says clearly to remember that the muzzle is actually an inch or more below the foresight and when shooting at close range it is easy to blow the gadget away to velocity heaven

[ganeshn]

......
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Need to check in different lighting, different conditions and heavier pellets. But I will not cross compare with Chronoconnect because in my shooting area I can eithet get light+echoes or trees above + no echoes. Chrony does not like trees. Chrono connect does not like echoes.

Oh by the way - I successfully shot my Chrony and dented a bit of metal - but it's still working.

Try sticking the LED strip on top the diffuser upside down, it may work in shaded area with no echoes.a 1-2" thick plexiglass or polycarbonate covering the display should limit the damages.

[Suyash]

Dear Benny
Thanks for taking time to the experiment . You can probably try more pellets, and The Difference Between Dieseled And Non Dieseled Pellets. It would be interesting to see the increase in velocity after dieseling

[bennedose]

Tried with 840 mg (13 grain) Diana Shot Flat head
SDB 65 - 175 m/sec = 574 fps= 12.8 Joules/9.4 fpe
Orion = 165 m/sec = 540 fps = 11.4 Joules/8.4 fpe
IHP 35 = 155 m/sec = 508 m/sec = 10.1 Joules/7.5 fpe

Interestingly the power values with the heavier 13 grain pellet exactly coincide with the power values that I got using the lighter 760 mg/11.7 grain pellets I tried yesterday.

Lesson for me: The consistent readings despite change of weight of pellet give me confidence that I am getting a true reflection of the power being generated by my rifles.

Did not use Chrono connect today.

I wil certainly play around with dieseling in due course.

[bennedose]

A brief calculation tells me that with a 13 grain (840 mg pellet) (in 5.5mm/0.22) you will need a velocity of 197 m/sec (or 650 fps) to generate 16.3 Joules/12 fpe
Using a 11.7 grain (760 mg) pellet (0.22) you will need a velocity of 207 m/sec (680 fps) to generate 16.3 Joules/12 fpe

When manufacturers advertise their rifles are producing "x fps) they do not mention the weight of pellet. Unfortunately i don't know how much 0.177 pellets weigh, but I think 11 grain pellets (about 710 mg) are "heavy" in 0.177. 11 grain pellets in 0.177 wil need to emerge from a rifle at 214 m/sec (700 fps). Lots of 0.177 (4.5 mm) rifles should be able to achieve 700 fps and this means that getting to "16 Joules/12 fpe" is far easier with 0.177 than 0.22.

Lesson for me:
"Penetration power" is not just about velocity, it is dependent on the area of contact. A narrow pointed object will penetrate at lower velocity than a broad object. A board of deal wood will "see" a 0.177 pellt as a sharp 0.16 sq cm object poking into it. The same deal wood will "see" a 0.22 pellet as a 0.24 sq cm object. That means that a 0.177 pellet hiting a deal wood board will be exerting 50% more pressure at the point of contact than a 0.22 pellet travelling at the same velocity

It is likely that 0.177 rifles wil start failing the deal wood test long before 0.22 rifles. I believe that as long as Indian law accepts the deal wood test as the legal limit, there is scope for increasing the power of 0.22 rifles by increasing the stroke volume/swept volume- i.e the volume of air that gets compressed in a spring piston.

[ckkalyan]

Congratulations on your new acquisition bennedose!

As long as the owner of the Chronograph doesn't get shot into the bargain, I guess it is all good!

[Reaper]

Congratulations on the new acquisition.

Surprisingly from your test data for both the heavier and lighter pellets it looks like the SDB is out performing it's completion in terms of power.

[Basu]

Dear benne,
My expectations increased with arrival of your chrony.
I wish to know any velocity difference taking place post tuning or not.
The effect of dieseling/detonation in terms of power.
My CC recorded 811 fps or 16.94 fpe highest in SDB with 11.6 grns RH while dieseling.This data could not convince me at all.
Hope some day this mystery will be unveiled.

Basu

[bennedose]

Basu it will be a while before I get into the nitty gritty of tuning again. I have been sitting in my comfort zone with 3 rifles giving me good and accurate performance. I simply lose the will to take any trouble to do tuning if I stand at 25 meters and manage to hit a 4 inch target 2 out of 3 times with any of my 3 rifles. I will have to pull out my old SDB 50 from storage to start fiddling with tuning, dieseling etc. I will get down to that in due course.


But there are several other minor things to be done. For example my Chrony/Chronoconnect comparison showed the latter to be consisten but 10-15 mps slower. I need to recheck that and if I can prove that Chrono connect is reliable with a 10% +/- value - no one needs to invest in a Chrony. Chrono connect will do the job - so that will also be a useful line of investigation

Secondly I need to try with different pellets which is easy.

The third thing is documenting the power/velocity of my rifles today so that I can see how they degenerate over time. That would be a guideline of how long these weapons last before they need a major retune/respringing/washer change.

And then there is the question of when (rather than if) I should invest in a Gas Ram rifle. Gives me something to do in my spare time....

[bennedose]

Maybe I have some good news for people who cannot get access to a Chrony, but are using Chrono connect on their smart phones.

Today I did a brief simultaneous comparison of velocity calculated by the Chrony, Chrono connect on the mobile and sound recording via Audacity

Just 3 shots(IHP 35, 0.22/5.5mm)

Shot 1:
Chrony: 148 m/sec
Chrono connect: 130 m/sec
Audacity - will talk about this below

Shot 2:
Chrony: 152 m/sec
Chrono connect: 134 m/sec
Audacity -

Shot 3
Chrony: 154 m/sec
Chrono connect: 134 m/sec
Audacity -

Note that all Chrono Connect values are consistent. They are also consistently lower than Chrony values and tend to show values 15-20 m/sec slower. However Chrono connect requires very precise measurements that I am unable to do. It asks for distance of device (phone) fom muzzle relatively easy) and distance of device from pellet path. This is not easy. At best it is a guesstimate. So I cannot tell whether Chrono Connect values will be higher or lower or accurate for other people. But on average I would guess that Chrono Connect will give values that are approximately +/1 10% of the real values. So they are not was waaaay out.

What is way waaay out is Audacity and here is a special interest area for Basu and me. Basu I will start a separate thread with the Audacity wavefoms and some estimates which I hope will answer the question that we have discussed from time to time - that is - exactly where to take the measurements from. I think this might interest you.

[Suyash]

Thanks Benne , for taking time to do the experiments and writing detailed description of them. Any further information and experiments would be appreciated