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12 FPE limit

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gonzav:
Curious about the way they speed check one's WFTF rifle at major FT matches.
Currently I have set up my HW97K for WFTF. I am shooting JSB Exacts 8.44 grain pellets at 799 fps average (11.96 FPE)
Sometimes it goes up to 807 fps (12.2 FPE) on one or two shots out of five.

What is the margin of tolerance do they allow for speed when determining FPE?
Is it shot over the limit and you are disqualified?

I am thinking of just entering Open Class to be on the safe side if certain venues and days where the rifle is shooting faster than 800 fps.

-Leo

I have not attended any major venues yet. But plan on at least going to the Crosman event in upstate NY and the Pyramyd Air Cup. Maybe the Nationals.

Scotchmo:
In the USA, 12fpe is a rule of the Division rather than the law of the land. AAFTA rules allow a 2% velocity variation over 12fpe to allow for possible chrono variations. As long as the 8.44gr reads under 816fps on the match chrono, you are OK. Many venues don't test for FPE.

nced:

--- Quote from: gonzav on March 13, 2016, 09:18:56 AM ---Curious about the way they speed check one's WFTF rifle at major FT matches.
Currently I have set up my HW97K for WFTF. I am shooting JSB Exacts 8.44 grain pellets at 799 fps average (11.96 FPE)
Sometimes it goes up to 807 fps (12.2 FPE) on one or two shots out of five.

What is the margin of tolerance do they allow for speed when determining FPE?
Is it shot over the limit and you are disqualified?

I am thinking of just entering Open Class to be on the safe side if certain venues and days where the rifle is shooting faster than 800 fps.

-Leo

I have not attended any major venues yet. But plan on at least going to the Crosman event in upstate NY and the Pyramyd Air Cup. Maybe the Nationals.

--- End quote ---
In the UK if a gun exceeded 12fps when tested it becomes a "legal issue" and even in the USA, since fpe will vary simply with atmospheric conditions variations in velocity, it's possible that tuning a gun to 11.96fpe would disqualify you for a lot of matches. I know that the National FT matches I've shot the guns were chronied with the pellet being shot before and after the match. I don't shoot WFTF but I do believe that those who do set up for 11-11.5ish fpe (about 780- 790fps with 8.4 grains) to compensate for "variables".

Those more knowledgeable than I please chime in!

HectorMedina:

--- Quote from: gonzav on March 13, 2016, 09:18:56 AM ---Curious about the way they speed check one's WFTF rifle at major FT matches.
Currently I have set up my HW97K for WFTF. I am shooting JSB Exacts 8.44 grain pellets at 799 fps average (11.96 FPE)
Sometimes it goes up to 807 fps (12.2 FPE) on one or two shots out of five.

What is the margin of tolerance do they allow for speed when determining FPE?
Is it shot over the limit and you are disqualified?

I am thinking of just entering Open Class to be on the safe side if certain venues and days where the rifle is shooting faster than 800 fps.

-Leo

I have not attended any major venues yet. But plan on at least going to the Crosman event in upstate NY and the Pyramyd Air Cup. Maybe the Nationals.

--- End quote ---

Leo;

From page 17 of the AAFTA 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 for the competitor."

As you can see clearly, the 2% variation is in the VELOCITY. Now, I do not know where Scott gets the 816 fps for an 8.44 grs. pellt, he must be using a different gravity value. Since California is a different Repubic, he may live near the galactic reactron where gravity is somewhat whimsical.
For the rest of us mortals, AAFTA selected a constant to transform weight into mass that takes into account a standard gravity and that constant is 450436.

And it is there for "Instrumental variances". So that your Chrony may read different from someone else's (the MD's) and you are still OK.

As Ed C. tells you, MOST of the shooters that shoot long range trips set their guns at between 11 and 11½ ft-lbs. just to be on the safe side. It would make little sense to fly 16 hours (New Zealand) and then be disqualified, so my gun is set at 11 ft-lbs. flat.

Over the years I have found variances between chronos of up to 5% (with the "Chrony" brand being the main culprit), so the 2% is nowhere near reality, therefore it still behooves you to take all the precautions possible.

HOPEFULLY, with the advent of the LabRadar, the AAFTA will make the investment needed to place a SERIOUS instrument at the Nationals wherever this may be. LabRadar's errors are of the order of 0.1%

At the World's Matches the procedure is slightly different, from page 16 of the WFTF CORE RULES:

"5.3 RIFLE POWER VALIDATION (Chronograph)
During training day (1 day before starting the competition):
5.3.1 It is mandatory that on the training day there is a power validation test to be done before
commencement of the competition.
5.3.2 During the training day, the velocity test/configuration can be made in any number of trials
without penalties/warning/etc….
During Competition
5.3.3 All rifles shall be chronographed daily.
5.3.4 At first test rifles that exceed the 12 ft. lbs or 16.3 joules limit, may be adjusted for a re-test
before the match starts.
5.3.5 The Marshall shall personally load each pellet, ensuring that it is not deformed or damaged.
5.3.6 Tests on subsequent days may be done at any point along the course as determined by the
Chief Marshal.
5.3.7 If a shooter fails a test, then the test must be repeated. A maximum of 3 readable shots may
be made.
5.3.8 Any failure at these subsequent tests will lead to disqualification from that day’s result.
5.3.9 Each time a unique sticker shall be attached to every rifle that has passed the test and the
chronograph speed recorded is noted on a master sheet.
5.3.10 The velocity test result is recorded in the score card by the Deputy Marshall in charge and a
signature/control sticker/stamp included. "

The table for WFTF is in page 34 of this document:

http://www.wftc2016.com/OfficialSite/includes/WFTF%20-%20Core%20Rules%202016.pdf

Hope this helps!






Héctor

Scotchmo:

--- Quote from: HectorMedina on March 13, 2016, 10:24:47 PM ---...
As you can see clearly, the 2% variation is in the VELOCITY. Now, I do not know where Scott gets the 816 fps for an 8.44 grs. pellt, he must be using a different gravity value. Since California is a different Repubic, he may live near the galactic reactron where gravity is somewhat whimsical.
For the rest of us mortals, AAFTA selected a constant to transform weight into mass that takes into account a standard gravity and that constant is 450436.
...

--- End quote ---
Hector,
Gravity has nothing to do with it.

As you stated:

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

Therefore:

12fpe=8.44gr * Square[800.27fps]/450436

and

Velocity = square-root[12 * 450436/8.44] = 800.27fps

800fps x 102% = 816fps

So if Leo always reads under 816fps using an 8.44gr pellet, it passes according to AAFTA rules.

I'm not saying that is a prudent velocity to tune for. Leo asked how they checked guns. The only "major" matches he listed in his plans were USA matches. So those are the rules (AAFTA WFTF Division) I used as the basis for my answer.

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