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Author Topic: WFTF target checker  (Read 1967 times))

Offline Scotchmo

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WFTF target checker
« on: January 15, 2018, 02:06:10 AM »
Morro Bay Airgunners club members, John Bergquist and myself have been working on WFTF target checkers to use at our future matches. The same ones used as the official WFTF target checkers. Brian Samson from the UK came up with the design for use at WFTF world matches. It is also a new requirement in BFTA rule matches in the UK. Seeing all the scoring fiascoes at major FT matches in the USA convinced me that something like this is sorely needed to help the legitimacy of USA Field Target.

The original Samson WFTF target checker design was set to 5.5fpe equivalency. The actual FPE of the checker is only about 1/4fpe. The equivalency is for the momentum produced, as the target mechanisms operate on momentum transfer. The equivalency rating is for an 8.4gr pellet at that FPE. Lighter pellets produce a little less momentum and heavier pellets produce more momentum for a given FPE.

I heard that the WFTF may be going to 4.5fpe as the disqualifying threshold when a target fails to fall. I setup our marshal's target checkers to be close to that standard. But I also wanted to use a target checker to qualify targets for a match by testing them on the bench. Using the 4.5fpe tester did not make sense for that function, so I set one of the the target checkers to produce only 3fpe equivalency. Our targets must pass the 3fpe target checker (black) before they are deemed ready to put into use. During a match, protested targets are tested with the marshal's 4.5fpe target checker (orange) and are replaced if they fail.

Three marshal's DQ target checkers (orange), and one technicians qualifying checker (black w/less preload).

I used the same spring rate as the plans specified, but used less preload in order to get the lower 3fpe rating. Higher FPE equivalency is achieved with different length spacers placed inside the piston. I made 1/4, 1/2, and 3/4 long spacers with which to fine tune the target checkers. The 3fpe checker uses no spacing, and the 4.5fpe uses the 1/2 spacer.

Three spacer lengths for various FPE equivalencies:

The spacers can be installed and removed fairly easily, so one could use a single target checker for both bench testing and marshaling.

The USA will be hosting the 2021 WFTF World match. Our club will still be shooting Freestyle and AAFTA classes which include WFTF. But we will be adopting many of the WFTF course rules, challenge procedures, signage, etc. Hopefully helping shooters prepare for a good showing at the 2021 WFTF World Match in South Dakota.

Edit: After some testing, I found that the 1/4" spacer is too short to stay engaged with the upper spring guide. It can get dislodged internally. The 3/4" spacer works fine and the 1/2" also seems OK.
« Last Edit: January 16, 2018, 03:22:20 AM by Scotchmo »
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Offline gokidd

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Re: WFTF target checker
« Reply #1 on: January 30, 2018, 01:09:31 PM »
Great work, Scott!
Thanks for sharing your results.

« Last Edit: February 01, 2018, 05:56:12 PM by gokidd »
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Offline dan_house

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Re: WFTF target checker
« Reply #2 on: February 01, 2018, 04:28:51 PM »
South Dakota? there's a club in south Dakota? Right next door in Montana terms :)

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Offline John E.

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Re: WFTF target checker
« Reply #3 on: March 02, 2018, 07:58:54 PM »
I'm not to sure about the South Dakota thing either. Not having been at the meeting I'll wait to hear why the decision was made. The checkers look sweet though.