Author Topic: TRIGGER LOWER LINK TEST RESULTS  (Read 11960 times)

Offline jeff124

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RE: THE TRIGGER
« Reply #15 on: July 20, 2008, 04:51:28 AM »
Thanks for the great pix, just what I needed.
jeff124

Offline scottinharwood

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RE: THE TRIGGER
« Reply #16 on: August 20, 2008, 04:00:54 AM »
You all might want to check me on this, but with back of the napkin calc's for the tune of the lower link, moving the contact bar out just lengthens the fulcrum distance on the lower link to the SEAR thus increasing the force needed to be applied by the trigger.  I looked at this by moving the new lower link fulcrum point from Chris's tuned location of 1/4 inch to the right only out to 3/16 inches forcing the whole lower link to be moved to the right by 1/16 inch.  The input fulcrum distance from the trigger remains the same and the output fulcrum length on the lower link gets longer.  The distance from the SEAR fulcrum point to the contact point gets longer also by the same 1/16 inch.  Ultimately, it looks as though  the force required in this will actually go up.  From the back of the envelop calculations, if you assume the original force required to be applied to the sear by the contact bar is 1.0, then the 1/4 inch tune by Chris drops the force input required at the trigger from a relative value of 1.38 to about 0.54.  With drilling the new hole in thelower link at 3/16 inches rather than the 1/4" of Chris's mod, you move the whole lower link and subsequently the contact point on the SEAR to the right by 1/16 of an inch; a force advantage.  Hower, the force reduction on the SEAR does not make up for the loss of advantage by moving the fulcrum point and the napkin calcs say that the new resultant force required would be a relative 0.762.  Worst case, there will be no change what-so-ever.  So to really see an advantage, I think you would have to have a different Lower Link, SEAR and SEAR fulcrum point - essentially a whole new trigger assembly.  I think Chris's change is the best you can do for the existing trigger components and trigger fulcrum points.  By the way, I used measurements off Chris's photos so there is some error involved.

Scott
AA S400Xtra 0.177, BAM B51 0.177, Crosman Discovery 0.22, IZH M-46, RWS-54 0.177, Crosman 1377C, Crosman Storm XT

Air Gun Tuner\'s Motto, \"At least do no harm to the existing airgun accuracy and power!\"

Offline scottinharwood

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RE: TRIGGER LOWER LINK TEST RESULTS
« Reply #17 on: August 20, 2008, 09:15:35 AM »
Hi Chris,

Did the mod, it works very well, the trigger is so light that my groups are getting more compact since I can hold the grip lighter too.

Scott
AA S400Xtra 0.177, BAM B51 0.177, Crosman Discovery 0.22, IZH M-46, RWS-54 0.177, Crosman 1377C, Crosman Storm XT

Air Gun Tuner\'s Motto, \"At least do no harm to the existing airgun accuracy and power!\"

Offline preez

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RE: TRIGGER LOWER LINK TEST RESULTS
« Reply #18 on: September 05, 2008, 08:21:55 AM »
Hey Scott, didn't mean to be rude by not replying, but I simply did not notice your last 2 posts from 3 week s ago.

Anyways, since I did the mod I had a chance to shoot and chrony the disco more. It turned out that doing the "hole mod" and cutting the trigger spring made the trigger too light and the sear dragged on the hammer and slowed the rifle down. This result might not be typical! But it happened to my rifle. I started fudging with the sear and dremel tool trying to shave some of the top of the sear that locks the hammer. That made the rifle unable to cock. I left it alone for awhile, thinking I would need a new sear ordered. Last weekend I approached the modified sear again with the dremel, shaped the top some more and developed a more pronounced notch for the hammer to lock into. I polished all mating sufaces nice and applied some moly on it. To my own big surprise it resulted in even better trigger, without the drag on the hammer, safe, pronounced 2 stage (1st stage maybe a tad long) but the break is much crisper than ever. Next time I have the disco open I will make sure to take some pics of the new sear. I definately do not reccomend this modification, as I feel that my result is pure coincidence.

I like my disco whole lot better now.

Chris
Bam B-26 .22, Hammerli 850 .22 HPA, Marauder .22

LITTLE HUMILITY GOES A LONG WAY!!!!!!!!! - Joe Cuz