Best conditions for chronographing...

[Clean Shot]

Hi all

Some of us wont have one, most of us will have a crombro, some a Skan, and a few something better.
The police and HO well god knows what they have..

So...

What are the best conditions for the most accurate results and is there a significant difference....??
Personally I have a crombro; I test outside in the daytime while it is either a little overcast or if sunny in the shade. Does having your rifle not on a level base make a difference.
My club Skan is in an indoor range in comparatively gloomy or less well lit conditions.

I've tried shooting at an angle in to the ground vs on a pod with the rifle leveled without seeing any significant difference...

on a 200 Bar fill my .22 Daystate PCP goes 11.52 - 11.67 using lightweight Exact Express.
Testing with a heavyweight pellet (I use Barracuda Match @21.1 gn) this gives 10.31 ish.

Thoughts..?

[angrybear]

If it reads the velocity, then it reads the velocity, end of issue.

The fact the Barracuda is that much lower suggests it is not very efficient in your rifle.

[Steyr]

velocity is - as above - velocity

The issue is how well one chrono measures and if it is within the manufacturers tolerances.

The way a chrono is essentially the same - a start beam is broken and a finish beam is broken. the time taken between these two points is the measure which all the subsequent maths and formula are applied.

However, there are various technologies at play here such as light - daylight from sunny to overcast or man made in a room/range.

Infra red seems to be less fussy re light and technically, can work in complete darkness.

I also believe there is radar technology but you will have to do your own research.

So long as it can read the time taken to go between start and stop and the distance is known then you should not be too far off.

Using heavier pellets in a PCP will usually (but not always) reduce the FPE and reverse in Springers as a rule.

Angles, wind. fog etc should not prevent a reading.

Muzzle blast - the gasses rapidly expanding behind the projectile can also fool the chrono.

Generally, the use of a moderator will reduce the speed of the projectile but not by a sufficient amount to worry about. the advantages of a mod is usually to reduce sound signature, tighten the group and to reduce felt recoil of the equipment you are using produces it.

Combros as a rule are more difficult to use with springers. The one time I lent mine to a spring shooter, the second shot decided to rearrange the coefficient of drag of my combro much to Robins amusement.

[ian321]

So it’s showing 469 FPS on the heavy pellets?

[mad man]

My combro reads really low if I use it out side bring it inside and it's perfect

[Phil Russell]

The chrono measures the speed of the pellet as it passes two sensors set a fixed distance apart. I guess that shooting at any angle that is not completely level across the sensors (and is thus the shortest distance between the sensors) could lead to a wrong reading due to the very small increase in flight distance between the sensors.

I use a Skan, indoors, set on a rest. I remember reading somewhere that Skan units are used by the Police.
Cheers, Phil

[Clean Shot]

cheers all for the reply's.
Clears it all up nicely.

Of course the heavyweight is just there to prove to myself that I'm not over our stupid 12 FTLB hard limit if I start using a heavier pellet.
TBH I never checked the FPS on the H+Ns (as I never shoot them otherwise) basically its like throwing bricks !

As when I purchased the rifle I wasn't aware of the differences in .22 and .177 I went with what I knew and have tried to flatten the trajectory as best possible with a lighter faster pellet.

Anyway I'm hoping to get myself a nice shiny new Walnut Red Wolf HiLite soon mnnnnnn (in .177 this time !!! )

Ta
Paul

[Cornishmolecat]

Surely colder air gives better energy as its denser

[angrybear]

Surely colder air gives better energy as its denser

It's measured over such a short distance, so close to the muzzle any difference in conditions or angle will have zero practical effect.