View Full Version : 1911 Leaf Spring

Gregory Gauvin
April 13, 2009, 05:19 PM
First, can someone explain to me how slamming the slide home on an empty chamber can damage the sear? Or does this only pertain to ruining a custom trigger job? I would think slamming the slide may allow the sear to "bounce" a little in the hammer notch, but I wouldn't think this would be enough to ruin the sear angle - unless done 1,000 times. Can someone explain?

Setting the leaf spring - I suppose you can set the right leaf (grip safety) to anything your really prefer, providing the grip safety works.

Center leaf - is there a "recommended" weight that the trigger bow/disconnector must have, say 10oz? Let's say you are given a flattened spring and must bend up your own.

Sear spring - same as above. What is the minimum weight that can be used without risking hammer follow?

James K
April 13, 2009, 06:08 PM
There are a couple of potential problems with dropping the slide that way, especially on a pistol with a fine sear engagement. The one of interest is that if the finger is off the trigger, the sear tends to release itself, allowing the half-cock notch to drop onto the sear. With a good sear, that will not be a problem at least once in a while, but some smiths do "knife edge" sears which can be damaged. This can happen with or without a round to be chambered. Also, since the hammer dropping onto the sear is part of normal operation of the pistol, a sear which is too fine and/or too soft will eventually fail in just firing the gun.

But why does dropping the slide cause the hammer to fall? Well, what happens is this. The slide and barrel go forward. The barrel is stopped when its bottom lug comes up against the slide stop pin. The slide stops when it hits the barrel.

While this is going on, the pistol frame is more or less stationery. But when the slide stops, it drives the frame forward. The trgger, loose in the frame, obeys Mr. Newton and tries to remain in place, which means it moves back relative to the frame. The trigger bow strikes the disconnector, which in turn strikes the sear, kicking it out of the full cock notch. That drops the hammer, until the sear spring reasserts itself and moves the sear to stop the hammer from falling.

If the sear doesn't return in time, a round being chambered can fire. If it does, it catches the hammer in the half cock notch and there is potential damage to the sear.

Let me state that in a normal "GI spec" pistol, I see no problem in dropping the slide from time to time and there should be no damage. Needless to say, like some other valid concerns, some folks go overboard on this and have fits if they see or hear of anyone dropping a slide. Such overconcern is usually misplaced.


Gregory Gauvin
April 13, 2009, 09:32 PM
I found an article at brownells. For a 2-1/2 pound trigger pull the smith sets the disconnect leg at 8oz, and adds in another 8 oz of weight for a total of 16 oz for both the sear and disconnector weight. Of course, this pull weight is a bit light for most and the author says he will add in trigger pull by adding in more sear spring. So I would say 8oz is a good minimum, with 10oz being a safe measurement.

Author also uses .018" on hammer hooks. I would probably keep it around .021".

April 14, 2009, 06:40 AM
Very excellent post by Mr Keenan. I would not reccomend cutting the hammer hooks to .018" unless you really know what you are doing and are very careful about handling a 1911 set up like that. .020" is plenty of clearance for a decent trigger pull.

April 17, 2009, 12:47 AM
Before I set the various sear spring tensions, I first polish the 40 degree ramp of the disconnector as well as the middle sear spring leg.
I've already polished the trigger bow and the flat face of the disconnector as well.
I then adjust the center sear spring leg tension so that it pushes the disconnector up positively. Not too much tension, but positive motion.
8 to 10 ounces seems ok for the left sear leg against the sear.
I ran across a sear spring recently where the left leg was dragging on the frame.
I ground the left edge of the spring removing maybe .015" to clear the frame.
When I set up a sear face, I make it parallel to the 90 degree hammer hook.
This effectively traps the sear when it is in the full cock position.
This geometry allows a trigger pull down to about 2.5 lbs., when used with a light main spring.
The idea here is the sear is trapped and will not follow.
The main spring plays a greater role in the trigger pull force when trapped.
This method is not for triggers under 2.5 lbs.

Harry Bonar
April 17, 2009, 08:58 PM
Right-on Jim.
Harry B.