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Gregory Gauvin
April 19, 2009, 08:23 PM
Doing some trigger work to my 1911. I took the leaf spring out, and noticed that the factory setting had the sear spring bent forward (more tension) than the trigger/disconnector center leg spring. I heard elsewhere, that generally, the center leaf and sear spring should be about the same.

In anycase, I removed some pretravel, took a hair off the sear spring (but still had more than center leaf), then did some trigger boosting. Trigger smoothened out, 90% creep gone, 100% improvement.

I dropped the slide to test for hammer follow. With trigger depressed, hammer will not follow. This means I have safe tension on the sear spring? I pointed pistol up, trigger not depressed, held gun very lightly, dropped slide, hammer did follow. I assume because I had taken so much pretravel out. So, I went back in and increased the center leg leaf spring even with the sear spring leg. Re-tested - perfect. Cannot get the hammer to follow. Trigger feels perfect.

Why wouldn't the factory have adjusted the two legs evenly? Is it because you can get away with less tension if you have more pretravel? Seems like the slide slamming would instead of having to overcome a certain amount of tension, have to overcome a certain amount of tension over distance before disengaging the sear.

If you wanted to increase trigger pull, would you increase the center leg, sear leg, or both? Is it a good thing to keep them even or is having more sear tension "safer", and enough disconnector tension to prevent hammer follow from a rebounding trigger?

Did I do good here, or should I not have taken tension from the sear leg, thus, keeping a gritty, creepy trigger and no hammer follow versus a much cleaner, smoother trigger with slightly heavier pretravel pull with no hammer follow?

It just makes sense to me that you can decrease the sear spring (to a safe limit) and increase the center leg until no hammer follow MORE SO than increasing sear spring tension, and to prevent hammer follow, increase pretravel and use a lighter center spring tension. Right?

Harry Bonar
April 20, 2009, 04:50 PM
Sir;
Forgive me, but I mean no ill but I don't think you should be touching your trigger!
The sear leg and the disconnector leg should be even but if you don't have any idea what you're doing this can be very dangerous! The spring legs are adjustible for certain conditions and this arrangement isn't necessarily so.
Harry B.

Gregory Gauvin
April 20, 2009, 11:10 PM
I'm quite familiar with the 1911, its function, and forced to mess with the trigger because I learned the hard way that Taurus really slops things together. Maybe good enough for a 1911 newbie, but not me. I also understand that a "factory" gun of course is going to be a little bit more liability tuned (ie, heavier, grittier trigger) than any custom piece.

Before I messed with anything, I weighed both the disconnector spring and sear spring tension. Pistol smiths doing custom jobs generally apply 8 oz pull weight to the disconnector spring, then add in another 8 oz for the sear spring for a total of 16 oz. The factory setting had 8oz on the disconnector leg, and about 12 oz on the sear leg. I reduced the sear leg spring a hair...around to about 10 oz. Slide was off, so the series 80 mechanism did not play a part in pull weight.

I understand reducing the sear spring is a bad idea to lighten/reduce trigger pull. This could lead to doubles, full auto, hammer follow...etc. I removed a hair tension from the leg not to lighten pull, but to help reduce friction between sear and hammer hooks to smoothen the break.

You need sufficient tension on the sear leg to prevent the sear from slipping out under the hammer hooks and causing follow. If you don't have enough tension on the trigger/disconnector leg, the trigger stays stationary in the frame while the slide slams forward and hammer will follow.

Let me simplify the question. If you are experiencing hammer follow because the trigger is staying stationary while the frame is moving forward when dropping the slide, you could increase tension on the trigger/disconnector leg to fix this. You could also (but WHY?) increase tension on the sear leg, making the break a bit heavier (to a point) so when the trigger recoils back, it doesn't disconnect the sear from the hammer hooks. Why would anybody (the factory) choose to put in a much heavier break than a lighter crisper break, with a heavier pretravel?

Gregory Gauvin
April 20, 2009, 11:52 PM
What is the effect of having too much tension on the disconnector (center leaf spring leg)? Any potential problems if going over the recommended 8oz?

JMBstudent
April 21, 2009, 11:25 AM
The purpose of the sear spring center leg is to assure positive motion of the disconnector up and down as the pistol cycles.
Pressure from the center leg considerably greater than required to assure positive up and down motion, simply adds to the trigger pull, as well as requiring more energy from the slide to force the disconnector down. This increased energy is translated to friction and wear of the tip of the disconnector, the frame hole that the disconnector rides in and the lower flat surface of the slide.
The disconnector is controlled by the sear pivot pin inside the square opening of the disconnector. Extra pressure here increases wear on the sear pivot pin and friction where the disconnector rides the pivot pin.
Additionally this extra pressure translates to wear and friction at the point where the center leg tip contacts the 40 degree ramp of the disconnector.
The trigger bow works against the lower flat of the disconnector when firing. Extra pressure here merely serves to increase wear at these surfaces as well.
For smooth operation, all of the disconnector contact points with the trigger bow, the center sear spring leg, the contact point of the disconnector and sear, the inside of the frame hole and the upper tip of the disconnector should be polished smooth.
In conclusion, there is nothing to be gained and much to be lost by setting the center leg sear spring pressure beyond what is required to achieve postive up and down motion of the disconnector.

Tom2
April 21, 2009, 11:43 AM
I have messed with 1911's as I have done with my other guns, but I just don't screw with 1911 trigger pull work at all. I do not assume I know exactly what I am doing and figure to leave that to trained personnel. That, and staking front sights. I have a better grasp of the Smith revolvers and have tackled that except for messing with sears themselves. I can get an improvement that is safe and reasonable without getting rad on stoning the hammer and sear, etc. Heck, a decent cleanup and better lube job can help if you do nothing else.

Gregory Gauvin
April 21, 2009, 07:15 PM
"In conclusion, there is nothing to be gained and much to be lost by setting the center leg sear spring pressure beyond what is required to achieve postive up and down motion of the disconnector."

Even with positive up and down motion of the disconnector, would it be true to say that if this is so, there still may not be sufficient tension against the trigger to prevent the trigger from rebounding back and causing hammer follow (when gun is griped lightly, and slide is released?)

JMBstudent
April 21, 2009, 10:07 PM
Regarding sear bounce. The way I prep the sear primary angle to match the existing 90 degree hammer hook angle the sear is trapped by the hammer hooks.
Therefore not likely to "bounce".
Further, once the pistol has fired, the disconnector has disconnected from the sear and any pressure on the disconnector once it has disconnected does not press against the sear.
I hope this helps. :)

Gregory Gauvin
April 22, 2009, 04:45 PM
Sear bounce and trigger bounce are two different things, right?

The sear can slip out of the hammer hooks (insufficient tension on the sear spring) OR the trigger and bounce back and disengage the sear (insufficient tension holding trigger forward in frame).

drail
April 22, 2009, 07:46 PM
When testing for hammer follow if you hold the trigger back it defeats the purpose of the test. The sear doesn't "slip" out from the hammer UNLESS the trigger hits it. By holding the trigger back it cannot bounce into the sear. If a sear "slips" out of the hammer's hooks then your spring tension on it is is WAY TOO LIGHT.

Gregory Gauvin
April 22, 2009, 10:59 PM
Makes sense. I heard to test for hammer follow by releasing the slide with out holding the hammer back, and with holding it back. If it follows when holding it back, increase sear tension. If it follows when not, increase tension on center leg of leaf spring.

If the hammer can not follow when trigger is depressed, then how can a weak sear spring cause multiple/FA condition?

JMBstudent
April 24, 2009, 10:26 AM
Hi Gregory,
It seems to me you are on the right track regarding sear bounce vs trigger bounce.
However, when I fire my pistol, I'm not releasing the trigger the instant the pistol fires. Thus I don't get trigger bounce.
Now competitors that are double tapping targets and looking for low split times, may infact lightly and quickly release the trigger to get super fast resets and low split times.
As I said before, when I set up a sear and hammer, I match the sear primary angle to the 90 degree hammer hook angle. This effectively traps the sear after the slide moves forward. It then takes a 2-1/2 lb pull from the trigger to light off the next round. I use the STI composite triggers for the light weight, so I don't believe even with a small amount of trigger motion, there is enough energy for the trigger by itself to trip the sear and fire the pistol unexpectedly.
With a different sear to hammer geometry, where the sear is not trapped, and the sear is only held in place by the sear spring pressure plus friction, I can easily see how trigger bounce, combined with a light (below 2 lbs), trigger could cause hammer follow and even full auto fire.
This is one reason I refuse to produce a super light trigger pull that does not trap the sear.

ddog
May 2, 2009, 06:52 PM
Hammer follow can happen if you will alter your center leaf going rearwards.

Sarge
May 2, 2009, 07:45 PM
Greg,

The internet is a poor place to ask for advice on how to tune a 1911 trigger, set sear springs, etc. Part of the problem is that many manufacturers don't follow the milspec regarding spring thickness, temper etc. so it's hard to tell what you've got there without holding it in my hands. Whatever you do, don't keep letting that hammer follow, even just in testing it. The process is hard on sears.

Get yourself a copy of Jerry Khunhausen's Volume One of "The Colt 45 Automatic: A Shop Manual" (http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=199119). Therein you will find specs and reference photos for springs, hammer hook depth, sear engagement and a myriad of other little things that contribute to a safe and reliable 1911. I've been building and rebuilding my own since the 70s and if I had this book when I started out, I would have saved myself a lot of headaches and expense finding out stuff by trial and error.

My only consolation is that I 'trialed and errored' my way to many of the same conclusions made clear by the book. Trust me- it's much better to have the book, than the consolation;)