760 Trigger creepiness

760 Trigger creepiness

Joined: March 1st, 2002, 12:22 am

October 31st, 2011, 4:41 am #1


Had a few minutes in the shop, worked on the trigger while i was running down what I thought was a leak.

Cleaned up the sear, took about .015 off the top, polished, and no change. Creeps and grinds a bit, then a crisp complete break.

Also noticed that the trigger seemed to move and move and move then break.  Hmmm....

Finally noticed I can seen inside the pump tube thru the sear slot and starting watching what was happening. During cocking, you can see the hammer move back, displace the sear, the sear snap into place and hold the hammer. So far so good. Then pull the trigger, and did this several times cuz I didnt believe it...... the sear pulls the hammer down, alot, as it pulls clear. So when the hammer bottoms out on the inside of the pump tube, the sear pulls free and clear of the hammer finishing the shot cycle.

Ive not been back inside the gun to see what the diameter differences are between the pump tube ID and the hammers OD, and what is acting as the fulcrum for the hammer. And now understand why the trigger moves soooooo much before the shot breaks.

Ok, so how does one stop the hammer from "dipping"down during trigger pull? find and fix the leverage point? button the hammer? modify the hammer spring guide and mount? custom build one?


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Joined: February 9th, 2006, 10:35 pm

October 31st, 2011, 11:27 am #2

I hadn't noticed the vetical movement of the hammer before. I just knew the take-up (or whatever you call it) of the trigger before it trips is very long, so I changed that (one of my secret herbs and spices). Also polished mating surfaces of the sear and used a little plastic-compatible grease with PFTE on all contact points. Not match grade, but a big improvement.
I thought about removing the little doohickey that prevents the trigger from being pulled while the bolt is open since it has a spring that puts more pressure against the trigger, but decided to keep it for added safety.

I plink, therefore I am.
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Joined: November 28th, 2002, 6:26 pm

October 31st, 2011, 2:07 pm #3

Had a few minutes in the shop, worked on the trigger while i was running down what I thought was a leak.

Cleaned up the sear, took about .015 off the top, polished, and no change. Creeps and grinds a bit, then a crisp complete break.

Also noticed that the trigger seemed to move and move and move then break.  Hmmm....

Finally noticed I can seen inside the pump tube thru the sear slot and starting watching what was happening. During cocking, you can see the hammer move back, displace the sear, the sear snap into place and hold the hammer. So far so good. Then pull the trigger, and did this several times cuz I didnt believe it...... the sear pulls the hammer down, alot, as it pulls clear. So when the hammer bottoms out on the inside of the pump tube, the sear pulls free and clear of the hammer finishing the shot cycle.

Ive not been back inside the gun to see what the diameter differences are between the pump tube ID and the hammers OD, and what is acting as the fulcrum for the hammer. And now understand why the trigger moves soooooo much before the shot breaks.

Ok, so how does one stop the hammer from "dipping"down during trigger pull? find and fix the leverage point? button the hammer? modify the hammer spring guide and mount? custom build one?


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
Then you could tweak for minimum clearance consistent with free hammer motion. You might have to relieve the back end of the hammer to clear the screw as the stroke progresses, but other than that it should be straightforward.

Something like this?



Steve
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Joined: March 1st, 2002, 12:22 am

October 31st, 2011, 3:26 pm #4


hmmm dont see why not, assuming that part of the hammer sets back enough to engage the set screw. Which is easily checked.....

The other thing I was thinking ws buttoning the hammer on both bands. Course the more prudent solution would be to figure out whats letting it rotate in the first place. I have a theory, but I need to look into it more


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
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Joined: February 9th, 2006, 10:35 pm

October 31st, 2011, 3:32 pm #5

Then you could tweak for minimum clearance consistent with free hammer motion. You might have to relieve the back end of the hammer to clear the screw as the stroke progresses, but other than that it should be straightforward.

Something like this?



Steve
Looks like the screw is going right up through the top portion of the trigger where it engages the sear.
Or would it actually be behind (or in front) of the trigger?

I plink, therefore I am.
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Joined: April 28th, 2010, 12:23 am

October 31st, 2011, 3:34 pm #6

Steve mentioned that as the action progressed foward depending how u have the screw set it might snag on the rear spring guide area.. otherwise no trig interference.
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Joined: February 9th, 2006, 10:35 pm

October 31st, 2011, 3:39 pm #7

In the picture the screw (orange) is right in the top part of the trigger where it engages the sear (yellow except in the area above the sear).

I plink, therefore I am.
Last edited by airgunandy on October 31st, 2011, 3:40 pm, edited 1 time in total.
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Joined: November 28th, 2002, 6:26 pm

October 31st, 2011, 4:10 pm #8

...the 45o point and thus clear the trigger on the side?

Or maybe it's just a stupid idea.

Steve
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Joined: February 9th, 2006, 10:35 pm

October 31st, 2011, 4:39 pm #9

Or one on each side of the trigger? Or would that be overkill?

I plink, therefore I am.
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Joined: November 28th, 2002, 6:26 pm

October 31st, 2011, 4:41 pm #10

...shouldn't matter much.



Steve
Last edited by pneuguy on October 31st, 2011, 4:46 pm, edited 1 time in total.
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