Air Pistol Trigger Blade and Weight Testing

jbshooter · Post by **jbshooter** » Fri Mar 25, 2011 3:59 pm

I have been experimenting with various trigger blades on my Morini 162 Air Pistol. After attaching the blade I recheck the trigger weight to ensure compliance with the 500g weight rule.
My question is this: Where is the weight hung from on a straight or flat trigger blade. The factory blades have grooves machined in them but the position of the groove may have no relation to where the shooter places his finger. The distance from the fulcrum to the finger pressure point can vary markedly between shooters. One could arbitrarily machine a groove in the face of the blade from where a 500g weight would comply, but the shooter may place pressure further down which would give the outcome of a lighter trigger weight.

renzo · Post by **renzo** » Fri Mar 25, 2011 9:55 pm

You may want to check ISSF rule 8.4.1.6.

jbshooter · Post by **jbshooter** » Sat Mar 26, 2011 1:31 am

By way of example I will put up a photo tomorrow.
The issf illustrations don't show a straight trigegr blade.

David M · Post by **David M** » Sat Mar 26, 2011 2:38 am

Easy way to stop arguments is use a small rat tail file (about 3mm dia) and put a groove across the trigger shoe at approx. 50% of its length. This stops the weight from slipping to the shoe and makes weighing easier.

ruig · Post by **ruig** » Sat Mar 26, 2011 6:25 am

Trigger pull must be measured placing knife-edge of the weight in the middle of trigger blade and no matter if groove exists or not.

A pistol cannot be approved by equipment control, if trigger blade so modified, that trigger pull cannot be measured with the barrel in its vertical position.

jbshooter · Post by **jbshooter** » Sat Mar 26, 2011 1:59 pm

The blade shown is one of many examples I have, all of varying lengths. They don't have a groove machined in their faces. A shooter can fail a random trigger weight test and be disqaulified if the judge hangs the weight further from the fulcrum.

David Levene · Post by **David Levene** » Sat Mar 26, 2011 2:42 pm

jbshooter wrote:The blade shown is one of many examples I have, all of varying lengths. They don't have a groove machined in their faces. A shooter can fail a random trigger weight test and be disqaulified if the judge hangs the weight further from the fulcrum.

From ISSF rule 8.4.1.6.2:-
"The weight of the trigger pull must be measured, with the test weight suspended near the middle of the trigger"

Note the word "near". If you set your trigger so fine that it won't lift "near" the middle then it's your own fault if you fail a trigger weight check.

renzo · Post by **renzo** » Sat Mar 26, 2011 8:17 pm

Just two hours ago I finished my biannual refreshing course as judge for National shooting matches, the professors being two I.S.S.F. class "A" judges, and having read yesterday this thread, I brought their attention to the question in the OP.

Both were concurring in ruling that no matter what could the shooter have done on the surface of the trigger (meaning transversal grooves), trigger weight must be checked with the weight blade near the middle of the trigger blade, as per rule 8.4.1.6.2

They even warned us (the alumni) that the mere existence of such a groove on the trigger blade (if manually made by the shooter with a tool) should be seen as an intent on the part of the shooter at "suggesting" to the equipment officer in charge of the checking procedures to put the edge of the test weight exactly there, and should be specifically disregarded.

Richard H · Post by **Richard H** » Sun Mar 27, 2011 6:56 am

Considering you're suppose to measure it in the middle if the line was actually in the middle and you "specifically disregard" that line did they tell you how too "specifically" measure the trigger weight wrong? I suspect they meant to actual check that the line is in the middle and not to "specifically disregard" it as that would mean measuring the trigger wrong. If the line is somewhere other than the middle then of cousre you disregard it and measure in the middle, but if the line is in the middle than that's where you measure you simply don't choose to measure somewhere else.

Alexander · Post by **Alexander** » Sun Mar 27, 2011 7:47 am

Richard H wrote:If the line is somewhere other than the middle then of course you disregard it and measure in the middle, but if the line is in the middle than that's where you measure you simply don't choose to measure somewhere else.

Yes. I understand this is exactly how it was meant. Thank you for clarifying.

Alexander

jbshooter · Post by **jbshooter** » Sun Mar 27, 2011 1:49 pm

My enquiry came about after I fitted a LP10 trigger shoe onto my Morini. As you know, the LP10 shoe has a different shape and is more adjustable. After positioning it in the correct place for my finger I found I had to adjust the trigger weight heavier (substantially heavier) to comply with the rules because the test weight hangs further outboard from the fulcrum in the steyr shoe than it does when hung from the groove in the morini trigger blade. This led me to see that the position of the groove in the morini trigger bears no relationship to the placement of my trigger finger (my finger was actually pressing on the bottom of the trigger). I seemed to have a choice between lighter trigger pressure using the morini trigger (because the weight is really hung from the wrong place) or adjustability from the steyr shoe. The only useful thing about the groove in the morini trigger is that it ensures all morinis have the same calibration, the shooter is free to place his finger anywhere along the lever and can even engineer his grip to best advantage. The issf rules only illustrate the weight placement on a curved trigger; what does does a judge do when presented with two equal pistols except that one has a straight trigger blade 2cm long and the other has a straight blade 3cm long? The shooter with the 2cm blade can have a perceived advantage. With regard to the comment that the weight is to be hung near the centre of the blade I have found that a +/-1mm weight shift was enough to determine a pass or fail. The real issue will arise at a random test after a match where a shooter can be failed due to the weight being hung in a different place by a different judge.

David Levene · Post by **David Levene** » Sun Mar 27, 2011 3:11 pm

jbshooter wrote:With regard to the comment that the weight is to be hung near the centre of the blade I have found that a +/-1mm weight shift was enough to determine a pass or fail. The real issue will arise at a random test after a match where a shooter can be failed due to the weight being hung in a different place by a different judge.

Which just demonstrates the stupidity of having your trigger weight set too close to the limit.

David M · Post by **David M** » Sun Mar 27, 2011 3:11 pm

If you are setting your trigger weight so close to the limit that a minor change fails the trigger, then you deserve to fail.
Set your trigger weight so that there is no chance of failure.
For Airpistol add a couple of coins (about 20g) to the weights and set it to lift them.
You will not feel the difference of 20-30g on a 500g trigger and it will pass any trigger weight test.
Too many people fail trigger weight with too close a trigger setting, even daily temperature can change the setting.
I repeat...........Do not set too close to the limit.

renzo · Post by **renzo** » Sun Mar 27, 2011 3:27 pm

Regarding the last post, I remember when entering my first nationals 25 years ago being told by the equipment control judge that it is easier to lear to master a trigger 50 grams heavier than to depend on minute factors like the one you mentioned. I found it was good advice, but being honest, I never surpassed 567 in registered matchesm maybe upper level shooters can find inconvenient such a setup.

Years later, at the 1995 Pan American Games, I took the oportunity to service my SP-CF Hammerli at the official booth, the first time they came to my country. When talking with the head armorer about the screw that chenged the trigger pressure from 1000 to 1360 grams (then used in each event) he told me that it woud be better to let the trigger weight set at 1400 and stop worrying about it changing. It served me well, though (again) I'm no world class SP shooter.

I would (in your place) use the trigger blade you're most comfortable with and get accustomed thru training and practice to the few extra grams you need to add to the weight setting.

Of course, only my two cents.