AAFTA Chrono testin...
 

AAFTA Chrono testing procedure for energy level  

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KPinWI
(@kpinwi)
Joined: 2 years ago
Posts: 36
2018-08-28 11:17:30  

Is there a AAFTA specification that relates to how airguns will be chronographed to check energy level?

This would spell out the distance from end of barrel/shroud to chrono front edge or mid way between sky screens for example and if it would be corrected back to muzzle or not. For example if muzzle was 1 yd from chrono then additional 5 fps etc would be added to arrive at the true muzzle velocity.I see where it is used at larger competitions, but have not found anything detailing the exact process.


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Scotchmo
(@scotchmo)
Joined: 1 year ago
Posts: 126
2018-08-28 12:11:56  
Posted by: KPinWI

Is there a AAFTA specification that relates to how airguns will be chronographed to check energy level?

This would spell out the distance from end of barrel/shroud to chrono front edge or mid way between sky screens for example and if it would be corrected back to muzzle or not. For example if muzzle was 1 yd from chrono then additional 5 fps etc would be added to arrive at the true muzzle velocity.I see where it is used at larger competitions, but have not found anything detailing the exact process.

Muzzle velocity readings are usually taken at 1/2 to 1 yard beyond the muzzle. That's only about 2 to 4fps different than the true muzzle (which is sometimes buried in the shroud).

At AAFTA velocity checks, they don't extrapolate back to the muzzle. They also allow 2% velocity overage to take into account normal variation in pellet/chronograph/etc. That amounts to about 16fps additional allowance.

Before the match begins, any guns that fails the velocity test can be adjusted to bring it into compliance.

After the match starts, there may additional testing requirements. If the first shot over the chrono exceeds the allowance, you'll get to try a second and finally a third shot. After three non-compliant shots, your out.

From the Handbook:

Energy Level

A. Airguns may not exceed the energy level permitted by specific
AAFTA Division Rules. The energy level is computed by pellet
mass and muzzle velocity, using the following formula:

Energy(ft-lb) = Mass(grains) * Square[Muzzle Velocity(fps)]/450436

B. Velocity readings may exceed by a 2% margin to account for
Chronograph variance.

C. Shooters will be given the opportunity to check their gun's
energy level prior to the start of a match, and will be allowed to:
adjust the energy level, replace the gun, or compete in another class.

D. Once a match starts, airguns found exceeding the allowed
energy level will result in disqualification of the competitor.

E. No energy-level adjustments allowed during the match. The
Match Director may tape or mark the gun as may be possible to
prevent tampering once the gun has been chronographed.

Chronograph Testing

The hosting venue should provide a Chronograph station so that
shooters may check the Energy Level compliance of their guns prior
to the start of the match. The Match Director reserves the right to
chronograph guns before, during, or after the match. The following is
the recommended procedure for Chronograph testing:

1. The shooter arrives at the designated Chronograph station and
hands the Marshal 3 pellets, along with his/her scorecard
marked with the make and weight of the pellets.

2.
The Marshal inspects the pellets, and may optionally weigh one
or more of the pellets on a calibrated scale.

3. The Marshal hands one of the pellets back to the shooter, and
instructs him/her to take a shot across the Chronograph.

4. The shooter gets up to 3 attempts to record a passing shot.

5.The Marshal records the final reading in the shooter's scorecard,
and signs the card.

 


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Hector J Medina G
(@hector-j-medina-g)
Member of Trade
Joined: 2 years ago
Posts: 291
2018-08-29 11:54:42  

As chronos advance in technology, specially those designed for airguns, there is no need to step back that 1/2 yard.

At WFTF meetings, the "Air Chrony"  is becoming the standard, so in the future, the tolerance may disappear from the rules/tables.

HTH

 

HM


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pistolero
(@pistolero)
Joined: 2 years ago
Posts: 317
2018-08-29 13:36:46  

The relatively-recent 2% "wiggle-room" rule was initially proposed by an individual known (by several FT shooters) to have knowingly competed over the power limit with both his Hunter class rifle and pistol. That individual had also bragged (again to several shooters) how easy "it would be" to get away with cheating, since Match Directors seldom do velocity tests (or enforce rules). Knowing all this, I was stunned when the BoG passed that wiggle-room rule.

Them's just the facts, Ma'am.

"No brag; just fact."- Will Sonnett


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KPinWI
(@kpinwi)
Joined: 2 years ago
Posts: 36
2018-09-02 17:03:17  

Thanks for responses. Looks like there is no meaningful defined testing process only an 2% acceptance criterian spelled out. I thought the 2% was due to cover the differences in results from different brand chronos, calibration tolerance when produced etc. I only run local shoots and probably never will run a Grand Prix event, but IMO a standard distance should be established from chrono for testing, most shrouds are only 2 in longer than the actual muzzle due to the endcap air trap design and could be considered the muzzle with less than 1 fps difference. Hector will you be selling the air chrono? How does it work, website doesn't disclose the mechanisim, maybe Radar?


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